If the Emperor had a Text-to-Speech Device

This article is awesome. Do not fuck it up.

This article contains spoilers! You have been warned.

Prepare yourself for pure undiluted WIN!

The Lord:
"You've nothing more to say to me? You come but to complain unendingly? Is never aught right to your mind?"
Mephistopheles:
"No, Lord! All is still downright bad, I find."
- Goethe's Faust, Prologue in Heaven.

A Youtube series created by Bruva Alfabusa, the show follows the exploits of Emprah himself in his quest to bring the Imperium of Man to its former glory, helped by the captain of the Custodes "Little Kitten", Magnus (now forgiven and with soul) and a hilarious cast of other major 40k characters. The series has become a complete success, mostly by poking fun on many of the memes, traditions and quirks of the 40k universe and the fandom but also by some very awesome scenes and, of course, great music.

Most fans agree that, while a wild and very unserious take on the 40k universe, the plot itself isn't actually that outlandish (apart from the Ultramarines capturing Magnus the Red...). If the Emps would wake up, it's pretty much a given that he would remove the worst parts of the Inquisition as some of the first things, while probably being an ass, as he always was. The unsure part is if the Emps would have learned from his 10,000 years of mistakes, which the series believes he has, deep inside. Doesn't help his temper though.

The so-called "TTS-verse" also includes Karl the Deranged's series Chaos Descends, and Eliphas the Inheritor's Behemoth trilogy. "Specials" are slated for story content that takes place outside the throne room.

Dramatis Personae

Starting off with a few characters, the series has evolved to encompass a fuckton of major and minor characters, with their own small arcs and all. It's not quite OotS level, but it's getting there.

Team Emperor

Emperor of Mankind: The Emprah, who's now able to verbally communicate with people after Techpriests installed a text-to-speech device on his throne. You know how Rouboute Guilliman is a 'jerk with a heart of gold'? Well the Emperor is a massive frothing plasteel dickbag with tourettes, with a heart of gold/platinum alloy studded with diamonds. Is currently planning to rebuild the Imperium after hearing the clusterfuck of stories from his Captain-General caretaker. He also has a pet Centurion (who turns out to be rather important), which he finds adorable, while finding Dreadknights abominable. He is a jerk, frequently insulting the Captain General with little reason other than he can (and because it's funny), and dialogue with Magnus implies he's always been a prick. Nonetheless he is ultimately a sympathetic character who wanted to create a better future for humanity and the comedic outrage he displays at all the bad news he gets is justified given how he frequently hears about costly victories that could have been avoided if the men in charge were less incompetent and how the Imperium has been destroying itself (usually because of the Inquisition). The Emperor has a new plan for defeating Chaos after the "starve them out by getting rid of religion" plan didn't work, but like before, he refuses to tell anyone what that plan is (although this time around, it's apparently not because he doesn't trust anyone, but because he doesn't want to spoil the surprise).

Custodes Captain-General (aka Kitten): Captain-General of the Adeptus Custodes and the only Custode who appears to have retained his sanity after the near-death of the Emperor, and for that matter one of the few sane humans in the Imperium. He serves as both the Emperor's personal caretaker and assistant, and pretty much the only person he regularly talks to and his main link to the outside world. Generally the only person the Emperor trusts and treats like a son, albeit constantly berating him whenever he does something stupid, or because he just feels like it. He also seriously hates Tau. One episode implies that it is because Shadowsun spurned him for the Greater Good (and also because he was a bit... fixated on the extremely y-onic shape of her nose), something he furiously and tearfully declares must be non-canon. He is named Little Kitten by his fellow Custodes, for "purring his way so far into their ranks", but his real name is a long seemingly nonsensical word salad supposedly based on his accomplishments... But given how he's been stuck in the palace for the last ten thousand years said accomplishments include things like "Goldilocks-Sunshine-Graham-Corncob". His frequent emotional outbursts despite the supposed emotionless state of the Custodes is intentional, and played for humor. After being forced out of the position of caretaker by his fellow Custodes, Kitten fell into a depression, to which Magnus ominously is taking advantage of by making Kitten his ally in making the Imperium great again and totally not get back at the old man. So far all he has done was kill a bunch of Lacrymoles that were impersonating the High Lords of Terra. It has been revealed that his uncanny knowledge of the outside world (considering the state of knowledge in the Imperium in general) could come from the Black Library itself.

Magnus the Red: The closest thing to a sane person besides the Captain-General (who plays the straight man depending on the situation). Retrieved from wherever within the Warp by the sheer plot-armor-powered efforts of Cato Sicarius and then brought to the Golden Throne, followed by the Emperor bullying Tzeentch in order to steal back Magnus' soul. Touched, he somehow managed to forgive the Emperor (sort of) and decided to help the Emps with his plan to fix the Imperium, but Emps being a jerk to him is starting to test his patience. The shiny new bike he was given helped with their reconciliation, though just how well his apparent heel-face turn has actually stuck is up for debate at best. The first thing he did with the bike was run over a bunch of kids on the street, possible foreshadowing? He may not be actively working for Chaos anymore, but he also quickly runs out of patience with his father and is attempting to fix the Imperium without his help, partly because he has serious doubts about his current sanity (which is kind of justified), and partly just to spite him. Magnus turns into a neckbearded daemon cyclops that is a bit reminiscent of his old model back in Epic, whenever he enters rage mode - usually prompted by any mention of space wolves. Is currently undertaking some obscure scheme with the unvitting aid of the Captain-General Kitten including attempted assassination of the High Lords of Terra and "borrowing" the Engine of Woes from Nocturne.

Rogal Dorn: Primarch of the Imperial Fists. Is revealed as the Emperor's personal Centurion, with whom he had nightly cuddling sessions prior to his reveal. He came out of hiding after Kitten brought up the topic of discussing the Space Wolves, where he vehemently suggested not to discuss the wolves to prevent Magnus from spazzing out. His extreme bluntness is shown to be less because he is an asshole and more because he is extremely oblivious and literal-minded and may have some form of autism (In episode 24 its greatly implied he is fully aware of everything going on including the emperors plans, implying he has some form of 'super sanity') , possibly due to using a fucking chainsword to scratch his head. Before his disappearance he used to consult his "magic pain glove" until his hand fell off. Despite his eccentricities and his inability to understand sarcasm, he can still make surprisingly lucid observations , such as that the end times are coming, and that not even the Chaos Gods will survive the potential end of all life in the galaxy. He even manages to, perhaps unwittingly, deliver one of the sickest burns yet on the Emperor, leaving him speechless. Actually, nearly every line he spouts is full of unintentional hilarity.

Imperials (So sorta good guys)

From right to left: Wamuudes, Custodisi and Karstodes.

The Pillar-stodes (Wamuudes, Custodisi, Karstodes): Some of the Emperor's personal companions from the Great Crusade days. After his interment into the Golden Throne, the rest of the Custodes have shed their armor as a sign of mourning. This, however, has also caused them to become fabulous hedonists (although somehow not to a Slaaneshi-tier extreme, they actually despise slaaneshi daemons the most, much to the Emperor's confusion), which greatly disturbs the Emperor. They also have no respect for their Captain General and don't even seem to remember that he's their superior, actually taking away his job as the emperor's caretaker by doing something for him. They constantly slip innuendos into their conversations, much to the discomfort of everyone involved. Except for Rogal; he's too literal-minded to notice. A running gag with them is that whenever the Pillarstodes come into a scene, they would dynamically jump in from nowhere with their own personal theme song. The three Pillarstodes appearance is based on the Pillar Men from JoJo's Bizarre Adventure: Battle Tendency; a group of fabulously well-built, half-naked Aztec vampire demigods seeking immortality. (they also make obscure jojo references at times)
Diavodes: Another crazy Jojo-Custodes (this one is based on Diavolo from part 5), he appeared out of the blue and asked Kitten and Magnus if they knew who he was, and was content to hear that they didn't. Once alone, he started to laugh maniacally, declaring that soon the new Emperor would be him, Diavodes! Also may or may not be a familiar face in disguise.

The High Lords of Terra: The people responsible for running the Imperium itself. Despite this the majority of the High Lords never really discuss or do anything to the betterment of the Imperium and just act senile, once planning to outlaw breathing for everyone but them. For this reason Magnus wants them all dead and handle governing the Imperium directly, but Kitten may have succeeded in convincing them not to fuck over the Imperium so much. Apparently they High Lords are commonly recruited from the Old Folks' planet, a retirement home so terrible that the High Lords have banned ever saying its name. There are currently 5 (technically 7 if you count the Head Scribe and Fyoder) High Lords featured, aside from the Captain-General.¨

Ecclesiarch Decius XXIII: The only non-senile High Lord aside from the Captain General, who legitimately takes his post seriously, even standing up to Fyodor and forbidding him to shed a single drop of blood from Terra's population (which Fyodor circumvented by using incendiary weaponry). For not screwing up the Emperor's plan, not being an overzealous bag of insanity, and rushing to try to save the Emperor when Fyodor stormed Terra's Palace he is allowed to stay leader of the Ecclesiarchy, even as the Emps is disbanding it/just changing every mention of God-Emperor to Man-Emperor, due to the fact that he and those who obeyed Emprah now are in charge of reforming the Imperium from the craphole it has sink in. Loyalty to the man rather than the word finally paid off. Just about everyone mocks him for his hat, which gets limp or...stiff depending on his emotional state. Hat Boners?!? He proved that despite the crap others give him, he can make some pretty rousing speeches on the fly.
Fabricator-General of Mars: The head of the Adeptus Mechanicus. Is so old that his voice stutters every time he speaks like a broken version of Stephen Hawking in addition to always speaking in little tunes. Constantly does nothing but insult his fellow High Lords for being made of flesh and recommend they swap out their fleshy bits for mechanical augmentations. According to other Magos, the Fabricator-General is also a massive junkie and party animal, and he invites the other high lords for margaritas on Mars.
Grand Provost Marshal: Head of the Adeptus Arbites, who does nothing but propose to make everything illegal. HE IS THE LAW.
Master of the Administratum: The head of the Imperial bureaucracy. A bit less inept than the rest of the high lords, he acts like your everyday senile grandfather.
Commander Militant of the Imperial Guard: The leader of the Imperial Guard. Doesn't do much, apart from comparing war to the good ol' days. Aware enough to know that the removal of minor luxuries (laxatives, breathing) may have detrimental effects on the Imperial Guard. Lays a sicknasty dilarius biznasty beat.

The Ultramarines

Marneus Calgar: Chapter Master of the Ultramarines. He's currently depressed and frustrated at the state of the Ultramarines where they basically win everything (due to their plot armor) as well as their strict adherence to the Codex Astartes to the point that it's no longer fun anymore. Due to this, his mood is eternally grumpy, only made worse by Sicarius' constant gloating. He actually seems to care deeply for the men under his command as he get extremely pissed off when Sicarius put his marines at unnecessary risk to achieve another victory to inflate his reputation. He also appears in a flashback during the second Tyranid war in Ultramar, where he did battle with the Swarmlord. While he put up a valiant fight, he found that they were equally matched, and thus, declared it a draw. Blatant hints point towards a deal he made with something to give his Chapter win more victories (hinted to have begun during the Second Tyrannic War), which he deeply regrets.
Cato Sicarius: Current Captain of the Ultramarines 2nd company. His persona's played as Cato's canon need to be a glory hound and the embodiment of the Ultramarines' plot armor, turned up to eleven, where he only cares for his advancement in the ranks of the Ultramarines and not much else. He apparently undertook the mission to capture Magnus the Red. Alone. Without his gellar field turned on, and his survival at such mission greatly pissed off Calgar to no ends, who was hoping he would die. He is also very verbal about his intention to take the position of Chapter Master, which greatly upsets Calgar (as Cato's dialogues largely implies that he's better than him and wishes for his death), to the point where he threatens to perform an "Imperial Fisting" upon Sicarius with his Gauntlets if he continues such thoughts. He also has a very egotistical, effeminate voice that can only be described as "the love child of tinnitus and a jackhammer", and he always refers to himself in the third person. It's goddamn hilarious.
Uriel Ventris: Current Captain of the Ultramarines 4th company. He doesn't have a lot of development yet, but appears as a close friend of Calgar and is the only one who's noticed the Ultramarines' theme of somehow always completing utterly suicidal missions. He comes to realize that some unknown force is tampering with space and time to rewrite history,(Probably has to do with an itsy bitsy little SHARD) covering up the Ultramarines past failures and playing up their successes to impossible levels, and starts to suspect that Calgar knows more about this than he's letting on.
Roboute Guilliman: The Emperor has regularly made a point of ordering the Custodes Captain-General to have him taken off life-support. Currently the only reason he's still alive is Kitten winning an epic duel in a children's card game against the Emperor. The result of his actions and the Codex Astartes horrifies his father. Going by the previous canon of Guilliman perhaps actually regenerating from the wounds that supposedly killed him, the Empra likely wants the time stasis field deactivated so he can finally get off his fucking ass.

The Salamanders

Vulkan: Primarch of the Salamanders. After the Ultramarines found the remaining artifacts of Vulkan in secret for the Salamanders, Vulkan returned to the chapter, where his return was greeted with great adulation (VUVUZELAS). He is notably quite crazy, and haunted by the ghost of Ferrus Manus. He speaks with a distinct African accent and loves friendship.
He'stan: Forgefather of the Salamanders. He is seen sleeping on an anvil on fire when Cato Sicarius delivered the remaining artifacts to the Salamanders, literally driving them through the wall of the fortress into the Forgefather's personal chambers. Thinking he found the artifacts in his sleep, he subsequently declares himself to be best forgefather.

The Raven Guard

Corvus Corax: Primarch of the Raven Guard. Appears at the end of one of the episodes. He's currently brooding away (and possibly stuck) in some dark room guarded by Salamanders, while writing edgy poetry in his journal. Magnus declared they were travelling to Nocturne to use the "Engine of Woes", whose name fits Corax's angsty personality; him hiding inside it might explain why he's on Nocturne in the first place.

The Dark Angels

Azrael: Chapter Master of the Dark Angels. He's depicted as an overly paranoid wreck, obsessing about Cypher, the Fallen Angels and constantly telling any non-inner circle member that reports to them that they're doing nothing suspicious and heretical. The fact that he had two newly indoctrinated inner circle members killed because they stumbled onto knowledge of the fallen (that he spat out in front of them) is played for laughs.
Belial: Grand Master of the Deathwing. His emo personality is hilariously turned to eleven whenever he perceives himself or his chapter as not being perfect, which is every waking second. This curiously allows him to become more reasonable than the rest of the Inner Circle. He has an effeminate yet whiny voice similar to Thurston Howell III.
Asmodai: The Dark Angels' Master of Repentance (which basically means "Violent Murdering" to him). He has an intense personality with a voice reminiscent of your stereotypical 1980s cartoon villain. REPENT, MOTHERFUCKER.
Watcher in the Dark (aka Snurko): A Watcher that accompanies Azrael, who is apparently the only one of its kind who can talk. It suddenly spoke of Cypher while in the presence of two newly indoctrinated inner-circle Angels, prompting Azrael to hilariously beat the shit out of it. His speech and mannerisms appears to be based off Orko from the He-man series.

The White Scars

Jaghatai Khan: Primarch of the White Scars. During the Horus Humbug, he managed to pull off the amazing feat of standing still for more than 20 seconds (while riding on a Razorback going at 200 miles per hour, but still). After the Codex announcement, he may be in Commorragh, as he desired to go fast and beat them in their jetbike races. Not much is known about his whereabouts right now, but it does mean that we will get to see him. Also the emperor has stolen at least one of his bikes from his room.

The Black Templars

According to Rogal Dorn, absolute lunatics, obsessed with "PURGING WITH MY KIIIIIIIIIIIIIN"... They enjoy their drop pods and ramming swords through xenos skulls. Actually not that far off canon.

Chaplain Grimaldus: Shows up in a filler short where he tries to ban the holiday of Sanguinala. The other Black Templars tell him he can't, prompting him to go to his bed and throw a loyalist tantrum.

The Space Wolves Corgis

Leman Russ: Primarch of the Space ~~Wolves~~ Corgis. Has been hiding in the Warp. Has a verbal staredown with Karamazov, then proceeds to relentlessly mock him while obsessing over wolves. He also gives a thorough dressing-down of the 3 branches of the Inquisition, as well as the Deathwatch, Tempestus Scions and Sisters of Battle accompanying them (delivering the infamous line "Daemons of Khorne are gonna eat ya out like ice cream sandwiches once your Red Rage begins!"). He even has his own version of the Navy Seal Copypasta. Despite being a viking, he has a pseudo-Scottish accent. Magnus has accused him of being a furry. He is currently teaching the Inquisition how to survive in the Warp by turning them into a drunken mob and killing innocent daemons. This include pranks of various sorts, such as crank calling Daemons, cockblocking a Daemonette at a bar (which actually kills them), and assaulting one of Nurgle's daemons with a fuckload of soap. After learning that Magnus is currently located in the imperial palace he decided to get out of the warp and go back to Terra, and is currently marching to the gate of Khaine, alongside with karamazov and Kalgor Draigo.

Space Wolves Wulfen: any mention of the Wulfen is normally echoed with someone shouting "Digganobz" in a demented manner. This is referred within a youtube short: the Grandmaster of the Grey Knights, sir Covan Leorac, was presented an image of the Wulfen and he called them Digganobz. And yes they really do look like Digganobz.

The Grey Knights

Kaldor Draigo: The Supreme Grand Master of the Grey Knights, who is cursed to wander The Warp for eternity. Centuries wandering unrealspace however, eroded Draigo's sanity, which not might be a bad thing as his craziness allows him to both stay in the warp without any trouble and murder daemons left and right (remember: the warp is a reflection of the minds of mortals and psykers can influence it to a higher degree. Draigo's insanity and powerful psychic talents allows him to shrug off the madness of the warp, simply because he believes without a shadow of a doubt that he can). He's made several appearances, first is annoying Fyodor's attack force after being banished into the warp by Magnus and later summoned by Kitten to handle Magnus' tantrum, which he does so in a split-second offscreen using inexplicable Mary Sue powers to defeat him. He now hangs around with Russ and company, and is the only one besides Russ who can safely traverse the warp sober and troll daemons without his head exploding. Has apparently been sending Daemons (in the form of ordinary villagers, with jobs and families) into the "Super Warp" by throwing vortex grenades at them (given that they're already in The Warp, the grenades would suck them to an even deeper version of The Warp).

Covan Leorac: A Grand Master of the Grey Knights. He appears in a short video where some Grey Knights report solid evidence of the Wulfen among the Space Wolves. However, Covan is absolutely convinced that they're Digganobz and not Wulfen, even hitting a Knight in the head for disagreeing with. Whether this is a jab at GW heavily basing the look of Wulfen hon Digganobs or is in conscious denial to prevent the Grey Knights from waging a costly war upon the Space Wolves (again) is up to interpretation.

The Imperial Guard

Sly Marbo: The One-Man Army, Hero of the Imperium!
Ollanius Pius: Makes a split second appearence at 15.00 on Episode 24 before being headbutted to death by Horus. (Shame on you if you dont know this super dude, so read his history now!) In another episode, the Emperor takes the time to set the record straight that while Ollanius did in fact sacrifice himself for the Emperor, a Terminator and Custodes quickly followed suit in order to not be shown up by a mere mortal human. He was not amused by their transparent attempt to outshine Ollanius.

Adversaries

Abaddon the Despoiler: Has yet to personally appear in the series, but has so far has been contacting various Chaos Champions to enlist their help with the next Black Crusade.
Fulgrim: Has yet to personally appear in the series, but appears to have already joined Abaddon in his plans. He makes his appearance as the person who called Lucius to get him to join Abaddon.

Lord Inquisitor Fyodor Karamazov: Inquisitor of the Ordo Hereticus and a colossal jerk even among inquisitors. When the Emperor disbanded the Inquisition, he went ballistic and led an entire crusade to Terra to purge what he thinks is heresy. Ended up in the Warp via Magnus for his troubles, after being trolled in a magnificent manner by being told he is a fragment of the Emperor. This was all the Emperor's plan for sending out the message in the first place, to lure in all the more destructive Inquisitors to get rid of them. He's not out of the game yet, though, and is determined to return to the Emperor. He has become substantially more crazy after Leman Russ' Warp Survival lessons.

Dominique: The sentient scribe servitor on Fyodor's Throne of Judgement. He comically makes fun of Fyodor on several occasions and generally breaks the serious atmosphere that the Lord Inquisitor tries to project. He also has a curious predilection for sandpaper cigarettes and a rapacious drug habit. Died inexplicably during the Inquisition's drunken rampage,most likely due to alcohol poisoning . Voiced by Gonzo the Great.

Ordo Malleus Inquisitor: One of the Inquisitors accompanying Fyodor. He appears as an Inquisitor brandishing bulky power armor, almost resembling Terminator armor (because it is, since it's a Grey Knight Grand Master, called "Grey Knight Leader" in the ending; on a side note, the Ordo Malleus has human size Terminator Armours in its possession). Is the most level-headed of the group.

Inquisitor Adrielle Quist: One of the Inquisitors accompanying Fyodor whom you'd recognize if you've ever seen them. A xeno fetishist, evidence suggests she is actually a tsundere for Genestealers, and only dreams of being held in the strong, manly arms of her Broodlord-kun. She appears to be the bad cop of the group with a short temper and a rough, Russian accent. She claims that the letter of disbanding inquisition was written by a genestealer cult under the Emperor's name. While stuck in the warp with Fyodor and the rest, she assaults Kairos after asking if he's a Genestealer, naturally not caring which of his heads answered "Yes". Even mentioning Genestealers in her presence causes her to fly into a berzerker rage. Later, during the Halloween special, she appears in a manner similar to Kaldor Draigo to beat the shit out of every member of a Genestealer Cult on Hive World Purgatory while still drunk off her ass before fading back into the Warp.

Ordo Hereticus Inquisitor: One of the Inquisitors accompanying Fyodor. He appears as an Inquisitor dressed in black and using a bolt pistol with a sight mount (which is exactly from the front cover of Dark Heresy). Don't let his soft-spoken tone fool you - this guy gets aroused at the thought of executing other people regardless of what they've done. He is in favor of the door-kicking-and-burning-building type of Exterminatus, just like a medieval witch hunter. He is possibly the same Inquisitor as the one in the mask (who snickers arousedly at executing friendlies and wonders were the mask came from).
Torquemada Coteaz: One of the Inquisitors who joined Fyodor's assault into the Imperial Palace. He shows up after Fyodor's forces was blocked off by a force of loyal Ecclesiarchy priests led by Decius in the palace, but breaches their defenses by throwing a barrel of Jokaero at the defenders. This plan causes Fyodor to lose any respect for him, which solicits a disheveled response from Torquemada, telling him to get off his Throne of Judgement and tell him to his face, or use his multi-melta to do what he's too pathetic to. Fyodor backs off and lets him leave. So far he appears to be the only sane Inquisitor, snarling at Fyodor to not execute the Emperor for whatever offense he may pull out of his ass. He's also busy with making a film, which is why he didn't stay to see Fyodor's plans go to the Warp.
Inquisitor Javerticus: An Ordo Hereticus Inquisitor and the most dedicated and charismatic of them all, and also an awesome singer and swordsman. Sadly, the Grey Knights don't seem to comprehend his awesomely dramatic greatness. Named after the obsessive Inspector Javert.
The Gods of Chaos: The gods here are less chaotic than their canon counterparts. More-or-less they just sit around and talk to each other, the way they did prior to the Emperor showing up and making plans to wreck their collective shit.
- Tzeentch is a petty schoolyard bully/prankster who also likes to engage in pointless overthought pseudo-philosophy, and it's unclear if he means it or if it's just part of him being a troll.
- Slaanesh is a hyperactive masochistic camwhore. Steals from Khorne and trolls with sexual innuendos.
- Khorne is the only half-way normal Chaos God (if that term could ever be applied to the Gods), who has yet to appear beyond screaming at Slaanesh for being a creepy whore. Has a fairly good relationship with Khaine, though, and they work out together at the gym. Never skips leg day, unlike the Emperor.
- Nurgle is the only one actually doing any scheming. Has a voice that's really hard to understand without subtitles, and is more focused on his waifu Isha than actually doing anything. Although he did invent a new disease called Crotch Rot, which is as nasty as it sounds.
- Malal makes several short appearances, conversing with the various gods on Spacebook where he declares he will ruin everyone once he becomes canon again by escaping the "Retconnian" (a dimension where the Squats, Horus' soul, and other things that don't exist anymore are banished to) and a second time is shown to exist in a pocket outside canon where he is able to influence things that are canon in subtle ways using the "Tyrant Star", a wandering sun that gives off black light and incites anarchy and chaos on whatever planet it shines on. It appears that his obsession to become relevant again is a harmful one, as Horus and a Squat talk him down from his attempts and console him when he breaks down crying about his futile attempts.
Lucius the Eternal: Slaanesh's premier champion, who sounds like what would happen if Mickey Mouse turned to Slaanesh and became a drag queen in the process (his first appearance is a direct reference to this). First shown fucking up some Imperial Guardsmen (in all senses of the word) with his warband, laughing like a maniac all the while. He then got a call from Fulgrim, inviting him and his band to join one of Abaddon's "huge parties", which he accepted. His absolutely creepy portrayal in the series is quickly becoming one of the scariest (and most enjoyable) things in the franchise, sorta an impressive achievement. Runs a prank show in his spare time, and posts the results to Spacebook.
Ahzek Ahriman: Most powerful sorcerer of the Thousand Sons. Appears in a short scene where he finally gets access to the Black Library, only to be dicked with, and eventually booted out by Cegorach. Decided to quit trying to get into the Black Library for a while and take a break, but decided against the latter after being summoned by Abaddon for the Black Crusade.
Typhus: Chaos Lord of the Death Guard. Has the voice of Gilbert Gottfried, which he uses to read erotic fanfiction for Lucius. Like the other chaos champions, he's been summoned by Abbadon for the Black Crusade.
Huron Blackheart: We cannot confirm his appearance in the series proper, but it appears that he is with Abaddon in the Season 3 intro, perhaps pointing to an alliance of sorts. Why in the all the names of Chaos he is there, only Alfa (or maybe his voice actor) know.
The Tyranid Hivemind: Attempted to hijack the Chaos Gods' warpchat, but was kicked after too many synapses attempted connections. The Emperor claims that talking to the Tyranid Hivemind is like talking to a herd of hungry sheep.

Others

FUCKING HORUS: Appears in the April Fool's episode, where he breaks into the Emperor's throne room and incapacitates him. The Emperor declares Horus can't win because he's all alone, but says he isn't as he gathered allies while he was clawing his way out of The Warp, all of whom are some of the dead/retconned/obscure characters in the fluff, like; The Beast (An Ork who waged one of the most successful WAAAGH!s in human history), Goge Vandire (The man responsible for the worst chapter in Imperial History after the Horus Heresy), Sindri Myr, the Megarachnids (A footnote insectoid race in the fluff, who were hunted to extinction by the Astartes in the Great Crusade.), the Squats (We all know who they are), Hermann Von Strab (One of the most inept commanders the Imperium has ever seen, who met his end in the 3rd War of Armageddon.), the Old Ones, the Techno-Barbarians of olden Terra, 3ED Old One Eye and SLY MARBOOO *cue explosions*. He subsequently declares himself as the new Emperor. Later appeared for real in the second Q&A in the "Retconnian" with Malal and the Squats, and calms Malal's tantrum like a parent consoling a child.
Ghazghkull Mag Uruk Thraka: Currently beating up the Overfiend of Octarius, as in official lore. It's still unknown where Ghazzy's gonna fit into things, though it will likely be to assemble all Orks into a single Great WAAAGH!!

Cypher: He has a very vague, mysterious plot involving the planet Orior and its STCs. This seems to take place not long after the Ophidium Gulf Crusade Incident, as the Dark Angels managed to locate him by tracking his ship. He also seems to be skilled at disguise, as he just manages to waltz right into the Thunderhawk behind Azrael without any further comment. He's on his way towards Mars with the Dark Angels.
Dolphan Gruss: A Magos Explorator sent to Orior by the Admech to investigate the planet's STC. He is very blunt and dismissive when dealing with "fleshbags", and does so while speaking with a French accent. His most remarkable feature, however, is a drill that replaces his right hand, which, predictably, makes him the butt of many anime-related jokes, much to his dismay.
Reimleiz the Theorist: An attendant techpriest whom the Emperor calls "random mechanicus guy". He's currently searching for a motorbike for Rogal Dorn to use, inside Jaghatai Khan's shed. Is incapable of making any statement without phrasing it as a question and is constantly asking himself trivial question for no real reason (such as asking if legs are actually vehicles driven by tiny snotlings). Also has a penchant for slapping his cyberdong on toasters, which many mechanicus adepts around the system appears to be visibly fixated upon. Voiced by 40k theories
Cegorach: The Laughing God, shown guarding the Black Library. He encounters Ahriman trying to enter and forcefully boots him out after a bit of trolling. He has a French accent.
Isha: Despite being a kidnapping victim initially, Isha is now in a relationship with Nurgle. She hates Tzeentch and Slaanesh, mocking the former and encouraging Nurgle to plague the latter.
Gork and Mork (or was it Mork and Gork?): Two dumbfucks who argue with each other in other people's conversations on Spacebook, with Gork not actually knowing he's using the Interwarp and trying to figure out how to use it while already on it.
Khaine: Disappointed and annoyed by all the young Gods around him, sounds like an old man beat-down by life. He mostly hangs out in the warp chat and goes to the gym with Khorne.

Felinids: The ultimate let-down.
Necrons: They appear initially in a mini-episode by Karl. Necrons all speak with low-quality Text to Speech devices, except for the Lords who can afford higher quality devices. Shennanigans ensue when an unnamed Necron Lord discovers that his lowly minions can't pronounce certain things, so now all necrons make roflcopter sounds as their war cries. SOI SOI MOTHERFUCKER
Ground Marines: Introduced as a short spoof episode after the release of Age of Sigmar, a group of Ultramarines determined to bring their superior selves to the service of "other Emperors" enter a portal and come out transformed as Stormcast Eternals, their appearance crushing a small group of Empire Flagellants. Text then appeared expressing condolences for Warhammer Fantasy fans. Although non-canon, it's a jab at Games Workshop's need to crowbar Space Marines everywhere (As the Stormcast Eternals largely resemble the Space Marines. Heck, their posterboy group even takes after The Greatest Of Them All with the blue, white, and gold color scheme).
Eliphas The Inheritor: Makes a cameo in the second Q&A episode having sent a letter to the Emperor saying "Dear Corpse Emperor, Furk You." The episode then cuts to him laughing manically thinking he's so clever before the Emperor psychically punches him, promptly shutting him up.
Little Billy: A running gag character in the series. His appearance is a psychic child who made himself a crude power-armor costume using cardboard boxes, with Alfabusa's grey and blue livery for colors. The gag about him is that Billy is constantly subjected to lethal/traumatizing events, yet still survives to appear again, leading to a joke that he is actually a perpetual. So far he's been: run over by a space marine attack bike, kidnapped and thrown into a Dark Eldar slave pit twice, and implied to have been molested by Lucius after contacting him using a psychic link and suddenly appearing before him and hammered in the face by a Deathwatch member before almost getting eaten by Tyranids in Behemoth. He's also apparently talked to the High Lords at least once, since the Grand Provost Marshal hallucinates him. To date the only good thing to happen to him is Sly Marbo rescuing him after some internal deb-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA-ting.
Hobo Guardsman: also known as "Hobo-chan." Like Billy, he exists to be traumatized by the grim darkness of the universe. First he becomes an unwilling recipient of Lucius' charity efforts, that being a sandwich made from "freshly milked daemonette milk", then later he gets harassed by the Adeptus Arbites for adding rat meat to his rations to make them more edible. Fed up with the bullshit, he decides to join Chaos, getting warped away before his planet is destroyed by Exterminatus.
Inquisitor Headsmash: Hangs around on a ship in low orbit waiting for heresy to occur. Has a heavily reinforced Exterminatus button which he gets a LOT of use of it - as the name implies, he hits it repatedly using his head. Has the enviable talent of hearing heresy from orbit.
Detective Bruce Norring: Appears in the Halloween specials. With most of the Inquisition missing, Bruce is put on the case of chasing down shady heretics on hive world Purgatory before unwittingly uncovering a Genestealer cult and nearly made into a genehost - only to get saved by a completely sloshed Inquisitor from the warp.
Calato: A Deathwatch Champion from the Dark Angels. Originally from BEHEMOTH, Calato served under Inquisitor Kryptman, spending more time irritably fixing recaf rather than fighting xenos. Calato later shows up trapped in the warp with Karamazov and the rest of the Inquisition, where he had the balls to call Leman Russ a dogfucker to his face. Naturally, Russ was not amused. Later they made up over a pint of Fenrisian Ale, with Calato drunkenly embracing Russ as his "uncle... dog... my duncle!"
Skarbrand: Appears in the Warp Hijinks special as a victim of a ding-dong-ditch prank by Leman Russ and Fyodor. Skarbrand refers to himself exclusively in the third person and, being a Bloodthirster, hates literally everything; he actually remains in the doorframe after answering, which he hates slightly less.
Kairos Fateweaver: Appears in the same special, where he tries his usual "Knights and Knaves" shtick on the Ordo Xenos Inquisitor, and gets fucked up for his troubles.
The citizens of Hive World Purgatory: Originally appearing in Alfa's Upper Hive games, hive world Purgatory appears a few times in the series proper. It's citizens are extremely idiotic and prone to murdering each other over the slightest suspicion. It's also been the victim of a recent Crotch Rot epidemic, and multiple Genestealer invasions.
The Citizens Of The Imperium: In special episodes where the Emperor answers mail from citizens of the Imperium (most of which is questions asked by watchers of the series), Loyalist humanity plus an odd Xeno or Chaos entity ask questions of him. These are supposed to by sorted by Little Kitten and later Magnus as well, but quite a few stupid ones get through to the point that without the aid of the cuddly Centurion, the Emperor's frustration causes Warpstorms which obliterate chunks of the universe.

The Order of The Primarchs Return(?)

During the season 3 intro, the silhouettes the miniatures of all the primarchs seems to appear in the order they will first enter the show, as the order roughly corresponds with their actual in-series appearances so far.

Rogal Dorn (although we don't find out it's Dorn until after Magnus turns up)
Magnus
Vulkan
Leman Russ
Corvus Corax (Not seen, but heard trying to unstuck himself in some warehouse in Nocturne.)
Ferrus Manus
Lion El'Jonson
Jaghatai Khan
Angron
Perturabo
Lorgar
Mortarion
Fulgrim
Alpharius or perhaps Omegon
Konrad Curze
Roboute Guilliman (although occasionally referred to
Sanguinius
Horus (although Horus has been seen in the April Fools and the second Q&A episode.)

Trivia

The Emperor's motivation for creating the Human Webway was obtaining Eldar prostitutes, who could take him much better than humans could. The other benefits were an afterthought.
The Emperor is plagued by a phantom-itch (courtesy of Nurgle) which caused his nose to continue itching long after it fell off and rotted out of existence. Tzeentch believes the frustration will cause him to explode, destroying humanity and causing him to become a new Chaos God.
The Emperor likes tacos.
The Emperor believes that Love Can Bloom will result in humans passing STDs onto Eldar, so he condones interspecies romance.
The Emperor's left eye was accidentally poked out by Rogal Dorn's iron halo while attaching him to the Golden Throne (prompting the replacement before the rest of his body decayed). The Emperor intends to somehow resurrect him to punish him for it (though now that's no longer a necessity). Actually, in older depictions of the Emperor's duel with Horus, it is one of the wounds inflicting upon him (he also broke many bones, burned the Emperor's fabulous hairs, poisoned him and a lot of stuff...).
Some of the Emperor's previous personas included Moses and Chris-Chan. Yes, really.
The Emperor's shattered psyche includes knowledge of the 4th wall. This is not always available.
The Emperor created the formula indicating when there is (almost) enough dakka. Only he himself and Kitten know it.
The Emperor approves of the Tau in theory, although in practice only those willing to engage in melee. So basically just the Farsight Enclaves.
In fact, the Emperor actually approves of any Xenos that isn't a threat to mankind. Absolute eradication is unnecessary if regulation suffices.
Despite his intentions for the Imperial Truth involving suffocating the Chaos Gods, the Emperor's attempts at atheism were in fact making an actual god of disbelief...according to Magnus.
The Emperor can shape the Astronomicon so that he can flip the bird to the rest of the galaxy.
Has a known hobby: Plays a children's card game (Yu Gi Oh) with a clearly cheesy, overpowered and unfair deck...that, like most cheese, was destroyed as soon as it came across a hard counter. Apparently Emprah still hasn't learnt the lesson about why using OP stuff is a very bad idea.
The Emperor has called for a second Council of Nikea. This one has nothing to do with Magnus; ironically, it's centered on the ~~Space Wolves~~ Space Corgis, and the fact that the friendly woodland critters of Fenris that the Wolves commune with are actually daemons. We've yet to see Magnus' and Leman Russ' reaction to the news, but it's guaranteed to be hilarious.
He has also ordered Logan Grimnar to deliver presents to all the good little boys and girls in the Imperium on Sanguinala.
While he has a number of colorful insults for his subordinates, including the primarchs, he also has pet names for his sons, such as "my little Magnymagic" or "RogalyDonDon."
The First Founding was originally named the Only Founding, this was renamed after Guilliman's fuck up.
The Emperor disapproves of the saying "Life is the Emperor's currency".
The Emperor's flaming sword sounds like a squeaky toy hammer (at least when he bashed Tzeentch's faces in).