Primarch

"Man must become better and eviler"

-Friedrich Nietzsche, Thus Spoke Zarathustra: A Book for All and None

The Primarchs were the twenty genetically-engineered "sons" of the Emperor. Using his own DNA in their creation, the Primarchs were designed to be far superior to even Space Marines: they were taller, stronger, faster and more intelligent. They were also incredibly charismatic and were well suited to their role as the generals and leaders of the Imperium of Man. Such a pity then that they ended up being bunch of squalling siblings who were responsible for plunging the Imperium into its current messed up state. Even the loyalist primarches contributed to screwing things up good and proper, by either disappearing, getting killed or failing to keep the Imperium along their father's vision.

Several of the Primarchs at the Triumph of the Ullanor Crusade. From left to right: Sanguinius, Mortarion, Magnus the Red, Angron, Jaghatai Khan, Lorgar, Rogal Dorn, Horus, and Fulgrim (it is possible that they are all Alpharius, but let's not get into that...)

History

Horus Lupercal being made Warmaster of the Imperium in Ullanor. From center counter-clockwise: Horus, the Emperor, Magnus, Mortarion, Lorgar, Angron, Jaghatai Khan, Rogal Dorn, Rogal Dorn's mustache, Fulgrim and Sanguinius.

The Primarchs were created in a secret underground laboratory on what used to be the Himalayas, under the tightest security. All of them were derived from a subset of the Emperor's DNA that served as a template, which was altered differently for each of the Primarchs; it is also thought that he engineered them spiritually as well using long-forgotten psychic techniques. As the Raven Guard discovered after the Emperor granted them access to the original data from the Primarchs' creation, many of the Primarchs' gene-samples were wildly divergent from the original template- some had long gene sequences deleted, while others had non-human DNA spliced into them for reasons only known to the Emperor. (A particularly intriguing discovery was one sample labeled "Subject VI", which had extensive amounts of canine DNA added to it.) However, due to insidious dickery and in spite of the safeguards the Emperor had set up, the forces of Chaos were able to spirit the Primarchs away from the laboratory and scatter them across the universe. Just as planned. Somehow, the Emperor knew his sons were still alive, but had no clue to where they could be, so he decided to go ahead with his Space Marine project. Using DNA samples from each Primarch before they were abducted, the Emperor created twenty legions of Space Marines, in what would later be called the First Founding.

Each of the young Primarchs were forced to adapt to the lifestyle on their new homeworld, something which would influence and mould them throughout their lives. The Primarchs rapidly grew to adulthood and quickly rose to power, often becoming the leaders of their world. As the Emperor crusaded to unify the galaxy he would occasionally stumble upon another long-lost son. When this happened, the Emperor would hold a celebration in honor of this discovery, give the Primarch their legion to command, then tell them to fuck off and start conquering worlds while he fapped to his favoured offspring. The Emperor was a dick like that.

The first Primarch the Emperor discovered was Horus, who would become the Emperor's favoured son. The majority of Primarchs somehow recognized the Emperor on sight, immediately pledging their allegiance to their father. A few (such as Leman Russ and Vulkan) only swore allegiance after being bested in a contest. Angron outright refused to follow the Emperor, preferring to die in battle along with his rebels in their fight against the oppressive Not-Romans. The Emperor simply shrugged and abducted his son, leaving Angron's followers to get slaughtered. Angron never really got over that dick move.

At the end of the period known as the Great Crusade, Horus, who had recently been promoted to the title of Warmaster, fell to Chaos and rebelled. It didn't take long for eight other of his fellow Primarchs to join his side against the Emperor, resulting in a full-scale civil war known as the Horus Heresy. Funnily enough, most of the Primarchs who sided with Horus were those who felt that the Emperor had taken a giant, steaming dump on them. So while the Emperor is the greatest tactician, biologist, warlord, and leader in the history of mankind, he's worse than a crack-addled transient junkie as a father.

Primarchs and Legions

Legion Number	Name	Homeworld	Name of the Legion	Allegiance	Current Status
I	Lion El'Jonson	Caliban	Dark Angels	Loyal? LOYAL	Alive, imprisoned next to Luther ASLEEP within a chamber on The Rock. The Lion will awaken once The Emperor tells him to do so.
II	+++Records expunged+++
III	Fulgrim	Chemos	Emperor's Children	Traitor	Daemon Prince of Slaanesh, ruler of the Pleasure World. Fulgrim's actual consciousness however, may or may not also be still imprisoned within his own body by the daemon who possessed him in the first place.
IV	Perturabo	Olympia	Iron Warriors	Traitor	Daemon Prince, ruler of Medregard.
V	Jaghatai Khan	Chogoris/Mundus Planus	White Scars	Loyal	Unknown, disappeared into the Webway while hunting Dark Eldar.
VI	Leman Russ	Fenris	Space Wolves	Loyal	Unknown, disappeared into the Eye of Terror with the 13th company but promised to return one day. Magnus supposedly knows where he is, but he isn't telling.
VII	Rogal Dorn	Inwit	Imperial Fists	MEGA SUPER Loyal	Assumed deceased, disappeared while boarding a Chaos cruiser during a Black Crusade. His skeletal hands were recovered and placed in shrines. Rumored to still be alive.
VIII	Konrad Curze	Nostramo	Night Lords	Batman	Deceased, willingly assassinated by a Callidus assassin. His body was never found.
IX	Sanguinius	Baal	Blood Angels	Loyal	Deceased, slain by Horus. May or may not be the Sanguinor.
X	Ferrus Manus	Medusa	Iron Hands	Loyal	Deceased, slain by Fulgrim and his head offered to Horus as a gift. Fulgrim still has the body. Some claim he is still alive on Mars, though it may be not actually be him.
XI	+++Records expunged (Possibly Malal?)+++
XII	Angron	Nuceria	World Eaters	Traitor	Daemon Prince of Khorne. Spend most of his time Getting Shit Done and being banished to the Warp for a hundred or so years after Imperum responds to his blood crusades.
XIII	Roboute Guilliman	Macragge	Ultramarines	ULTRA Loyal?	In a stasis chamber after his throat was sliced by Fulgrim with a poisoned sword, so he is perpetually on the verge of death but technically still alive. Rumored to somehow be regenerating his mortal wound, despite being in a stasis field.
XIV	Mortarion	Barbarus	Death Guard	Traitor	Daemon Prince of Nurgle, ruler of Plague Planet. Banished by Grey Knights.
XV	Magnus the Red	Prospero	Thousand Sons	TraitorI never asked for this	Daemon Prince of Tzeentch, ruler of the Planet of Sorcerers. Wrecked the Space Wolves' homeworld and most of their upper command structure for the lulz.
XVI	Horus Lupercal	Cthonia	Luna Wolves/ Sons of Horus/ Black Legion	DOUBLE TRAITOR	Utterly, completely, absolutely, unbelievably, mindbogglingly deceased, utterly annihilated at the hands of the Emperor.
XVII	Lorgar Aurelian	Colchis	Word Bearers	Traitor Prime	Daemon Prince, ruler of Sicarius. Is spending all his time meditating in the warp, so Lorgar rarely appears in person anymore.
XVIII	Vulkan	Nocturne	Salamanders	Loyal	Lives, location unknown (possibly Trazyn's museum)
XIX	Corvus Corax	Deliverance	Raven Guard	Loyal	Missing, last seen heading for the Eye of Terror to atone for his sin of using a legion of mutants he accidentally created to supplement his forces, only to euthanize them after the Horus Heresy. Some believe he will return.
XX	Alpharius Omegon	They're not telling	Alpha Legion	Fuck knows	Alpharius may or may not have been killed by Guilliman(The Ultramarines suspect they may have only killed a body double). No news on Omegon (as nobody outside the Alpha Legion was aware he even existed) but he may or may not have been one of the founding members of the Grey Knights.

It Sucks To Be Loyal

An accurate retelling of the final stages of the rebellion.

Traitors

• General downside to those who became Daemon Princes is that the further they go from the Eye of Terror, the more their power wanes;
• Horus was killed by the Emperor during the Siege of Terra, who utterly destroyed his soul. His legion enshrined his corpse until the Emperor's Children stole it. Fabius Bile managed to successfully clone him, but Abaddon killed the clone to cement his position as his successor as Warmaster of Chaos. Horus is very dead, but that was his fault for being a fuckwit.
• Angron is a Daemon Prince of Khorne. Still gets shit done, but did get his arse handed to him by the Grey Knights on Armageddon.
• Mortarion is a fucktwit who rarely does anything of interest (still sulking over his eternal existence as the thing he hates the most), but is a Daemon Prince of Nurgle. Got some open heart surgery, courtesy of Draigo/Ward.
• Fulgrim's soul was trapped in a painting while his body was possessed by a daemon for a brief time before swapping places with the daemon and taking its powers (or so he claims). Later becomes a Daemon Prince of Slaanesh.
• Lorgar is a lazy fucknut who does nothing since they fled to the Eye of Terror, but still a Daemon Prince of Chaos Undivided. Taught Abaddon how to summon daemons.
• Magnus the Red is... derping out, and screaming Just as planned every time something happens, but he's a Daemon Prince. He sometimes also gets shit done, leading armies to the Space Wolves' planet and screwing with the Imperium, keeping his big red trollface on all the time until he gets his ass tossed back into the Warp. Occasionally mopes about how he never wanted to be a traitor originally.
• Perturabo becomes irrelevant after he goes on to drop largely out of post-Heresy fluff, but is still a Daemon Prince of Chaos Undivided. Helps Failbaddon in a couple of Black Crusades by giving him some Daemon Engines. It doesn't really help, but it's more than Lorgar's done for Chaos Undivided.
• Konrad Curze allowed a Callidus assassin to infiltrate his lair and kill him, apparently wanting to die after becoming the very thing he fought against.
• Alpharius, Omegon....or one of them is officially "dead" by Imperial records, slain by Guilliman. However, due to the labyrinthine schemes of the Alpha Legion and body-double tricks sanctioned by Alpharius (I.E: Surgically altering his doubles to look like him and feeding them his blood to temporarily give them Primarch powers, making it nearly impossible for anyone to tell who the real Alpharius is), even the Ultramarines aren't sure they killed the real deal.

Loyalists

• Ferrus Manus was killed by Fulgrim during the Drop Site Massacre. His body was not recovered, so some Iron Hands think he might still be alive. But the fact that he was decapitated by Fulgrim after being defeated and had his head delivered to Horus makes this claim fairly dubious. Just don't say that to the Iron Hands, though. Unless you want free open-heart surgery from a ceramite and steel power fist.
• Sanguinius was killed by Horus. His body was recovered, and he's the only Primarch who doesn't have any legends about returning, though there are some theories on the identity of the Sanguinor. For what it's worth, Fear to Tread shows that the Sanguinor is indistinguishable from Sanguinius himself and had enough power to appear in the mind of an Apothecary shortly before the Blood Angels were deployed to the Signus system.
• Lion El'Jonson returned to Caliban only to discover that his friend Luther had stabbed him in the back. THAT LUTHER HAD A PLANET-WIDE PARTY AND EVENTUALLY PASSED OUT INTO A COMA AFTER DRINKING 200 TANKARDS OF SPACE WOLF-GRADE ALCOHOL. He sleeps deep within the Rock, originally on life support and now fully-healed (but none of the Dark Angels seem to know this). Perhaps this is a sign of a coming advancement of the storyline, DUN DUN DUN! (Please no, not another Age of Shitmar)
• Genghis, er, Jaghatai Khan disappeared into the Webway after chasing a group of Dark Eldar. The White Scars think he will return someday, and when you consider the fact that time is just as weird there as it is in the rest of the Warp, there is a small possibility he's still around.
• Leman Russ disappeared into the Eye of Terror but promised the Space Wolves that he would return for the Final Battle. Magnus appears to know where he is now, but he sure as hell isn't telling the Space Wolves. Reports during the Thirteenth Black Crusade claim that a figure matching Russ's description was seen leading the 13th Great Company have surfaced, but were never verified.
• Rogal Dorn disappeared during a Black Crusade in a desperate ship boarding action. Only his skeletal hands were recovered and enshrined. Debate rages about whether the zerg rush of World Eaters killed him, or whether he's still out there, death-punching Traitors with his fuck stumps.
• Roboute Guilliman is perfectly preserved in a stasis field, seconds from death after he was poisoned by Fulgrim. It is rumored that he is healing, even though it is impossible for anything to change inside a stasis field (As time is literally frozen inside stasis). Most people credit the healing to be the power of the Emperor, which says something about the Imperium as that's considered a valid argument. It says something further about the setting in that a number of fans believe that this is a valid argument. This may be true following the Iron Heart device in Angel Exterminatus healing someone in stasis, very very slowly.
• Vulkan got the shit kicked out of him during the Drop Site Massacre, whereupon his fluff split into two mutually-exclusive paths:
  • Codex: Space Marines states that his body was never found, only a book containing only the names of nine powerful relics and a bunch of annoying riddles as to where they might be found, penned by Vulkan himself. In the 41st millennium, the Salamanders believe that he is still alive and that collecting the nine relics - they've found five so far - will reveal his location.
  • In Vulkan Lives the big V had to be dragged into a Thunderhawk in bloody tatters. Kurze captured him and tortured him to death... repeatedly; Vulkan would not stay dead. After an indeterminate amount of time and deaths, Vulkan managed to escape by teleporting himself into orbit around Macragge and reentering its atmosphere. When he recovered and learned that Kurze was planetside, he flipped out and went after him. A well-meaning Perpetual stabbed him with a fulgurite (a spearhead-shaped piece of stone that contains a bit of the Emperor's power), hoping to either cure his madness or kill him for good. Now apparently dead, Vulkan was put in a stasis capsule inscribed with the words "Unbound Flame," with an honor guard of Salamanders until his remains could be returned to Nocturne. As of the end of Deathfire, he somehow managed to return to life again, although there's no indication as to whether or not he's still a Perpetual. And then as of The Hunt for Vulkan, he's still alive in M.32, after the wounding of Guilliman. He's apparently been wandering the Imperium for a millennium fulfilling his own oaths, but returns to Terra to take command of the counterattack on The Beast. He hints that Dorn is also alive, meaning he is either privy to some secret information, doesn't know of his brother's death, or is going insane.
• Corax disappeared into the Eye of Terror as an atonement for putting down the mutant hordes he created in trying to create Space Marines out of desperation. Quoth the Raven: "Nevermore." He is probably derping around in the Eye like this: https://www.youtube.com/watch?v=rIX_6TBeph0

So the surviving traitors (with the possible exceptions of Alpharius and Omegon) are Daemon Princes (which, ignoring the brain-rape, fucking rules) while all of the loyalists are dead, have disappeared, or are in comas. The chapters have legends which hold that the Primarchs will return and heal the Emperor, launching a new Great Crusade. Note: when GW says “disappeared” they actually mean “we are going to bring them back in a massive deus ex machina”. No they don't. They're not idealistic. Well, seeing what they did with FB in the End Times one may hope they would actually do move the plot of 40k past 999.M41 so that they can all come back and die again. Then again, seeing what happened to Warhammer Fantasy after the storyline was advanced, it's probably best to let things be.

Two Missing Primarchs

Who are the two missing Primarchs, you ask? Sigmar and Archaon (depending on how WHFB fits in with 40K, if it does). Or maybe (per /tg/ canon) Rachnus Rageous and Tialoc Ekans. Samus and Guts are also contenders. It is also highly possible that the XI Legion Primarch has now become Malal and the Sons of Malice Chaos Space Marine warband are the remnants of the 11th Legion (Possible, because Malal's sacred number is 11 and the two unknown legions are the II and the XI) ...

Okay, fine. Nobody really knows. What has been established is that they got killed for some reason and the existence of their Legions was wiped from record by the Emperor. The surviving marines from their Legions were then allegedly gobbled up by the Ultramarines, for some retarded reason.

Actually... the wording about the Ultramarines getting a boost in numbers after the erasure of the two Legion's might not mean that. It could just mean that the Ultramarines took their would-be recruits and dakka, and perhaps their recruiting worlds too.

Games Workshop have mentioned Primarchs besides the eighteen above on other occasions, but they backtracked since. Back in the first edition of Warhammer 40,000, all twenty First Founding Chapters were known, as were their Primarchs (though, at the time, the Primarch was just the first Chapter Master). Of these, the Valedictors and Rainbow Warriors were declared in a later White Dwarf to have been founded after the Second Founding.

Later, in the short story Hell in a Bottle from the novel Into the Maelstrom, a chapter known as the Iron Hearts get fucked over by a Chaos Lord. The short story also mentions that the Chapter has a Primarch known as Rubinek. Of course, this was just a huge cock-up on the author's part, who himself admitted that he meant Chapter Master.

The Horus Heresy novels fill in some of the blanks, but they still leave a lot of questions open. In The Lightning Tower Rogal Dorn says that the lost Primarchs' disappearances were "separate tragedies", so it seems like they disappeared in two different incidents. Deliverance Lost suggests that whatever happened to the missing Primarchs occurred sometime before the Emperor found Corvus Corax, as Corax asked the Emperor why there were only sixteen other Primarchs waiting for him if he was the nineteenth (it's unsure whether this was referring to him being the Primarch of the nineteenth Legion, or him being the nineteenth found); the Emperor avoided the question, claiming that "it would be a discussion for another day". This is no longer the case, somehow, as he is now the third-to-last primarch found, right before the second missing primarch. The First Heretic specifies that the missing Legions were purged at least 43 years before the Drop Site Massacre, so we can conclude that neither one took part in the Horus Heresy. At the same time, members of the Word Bearers Seventh Company travelling through time with Ingethel the Ascended reveal rumors that the surviving members of the lost Legions were folded into the Ultramarines (their Chaplain thinks the rumor is a load of grox-shit, but their Captain does note that the Ultramarines are on record as receiving an increase in troops). Finally, it also adds that the remaining Primarchs had to swear an oath never to speak of their missing brothers and that the missing Primarchs' corresponding legions were personally purged by the Emperor, so it had to have been something extraordinarily bad. Leman Russ mentions in Prospero Burns that the Space Wolves had fought other Space Marines before the attack on Prospero, which may have something to do with the purge. A senior Space Wolf describes Russ' "wyrd" as being "the Emperor's executioner". Several books since have backed this up. In The Dark King, when asked if he will report the Night Lords for censure, Dorn remarks that he feared to add another empty statue to the Emperor's palace, implying that the missing legions were exterminated for committing severe atrocities. Gene-seed flaws might have played a major part- in Fear To Tread, Sanguinius admits to Horus that he had not told the Emperor about the Red Thirst because he feared that the Emperor would purge the Blood Angels in the same way as the missing Legions. In Scars there's a reference to rumours and "whispers of past atrocities" that only a Primarch could kill another Primarch. Russ also turns up and talks a bit about fighting Magnus, and the resulting "shame". So if he's responsible for offing one or two of his brothers, they must've done something pretty fucking heinous.

Out of universe, Rick Priestley admitted that the unknown legions were supposed to be a reference to the three Roman legions wiped out in the Battle of the Teutoburg Forest, whose numbers were never reused after they were slain to a man by German barbarians (as well as a way to let fans design their own Legions to fill in the gaps for themselves). Clearly he didn't think out the implications that this would have on the setting.

Rules on the Tabletop

Thanks to Forge World, not only do we have models for the Primarchs, but rules as well. As you can guess, they are ungodly rape machines who can easily win their points back and more. That's not to say they're invincible, though; they can still be killed if you screw up badly enough. All currently released Primarchs have the following statlines:

	WS	BS	S	T	W	I	A	Ld	Sv	Points
Horus:	8	5	7	6	6	6	5+1	10	2+/3++	500
Angron:	9	5	7	6	5	7	6	10	3+/4++	400
Fulgrim:	8	6	6	6	6	8	5	10	2+/5++/3++ in CC	380
Mortarion:	7	5	6	7	7	5	5	10	2+/4++	425
Ferrus Manus:	7	6	7	7	6	5	4+1	10	2+/3++	455 or steal his hammer for 415
Konrad Curze:	8	6	6	6	6	7	5+1	10	2+/4++	435
Vulkan:	7	5	7	7	6	5	4	10	2+/3++	425
Lorgar:	6	6	6	6	5	6	4+1	10	2+/4++	375 or Chaosify him for 450
Perturabo:	8	6	7	6	6	5	4	10	2+/3++	455 or give him Forgebreaker for 490
Rogal Dorn:	8	5	6	6	6	5	4	10	2+/4++	385
Corvus Corax:	7	6	6	6	6/5	7	6/5	10	2+/5++ or 3+/5++	450 or fuck him over for 350
Alpharius:	7	7	6	6	6	6	5	10	2+/4++	415
Guilliman:	7	6	6	6	6	6	4+1	10	2+/4++	400
Magnus the Red:
Leman Russ:
Jaghatai Khan:
Lion El'Jonson:
Sanguinius:

Each of them have one or two close-combat weapons, all of which are AP2 or 1, backed by some decent gun to lay some dakka down while they run to the glorious melee. Their Primarch rule grants them the combined benefits of Fleet, Fearless, Fear, IWND, Eternal Warior, and Adamantium Will, and as ICs they can join squads as well (though most of the Primarchs are better run solo). Each of them have a page worth of special rules and unique wargear, some of which is stupidly powerful to the point of broken, but that's OK since even the cheapest of the Primarchs costs more than 350 pts. and eats an extremely valuable Lord of War slot that might otherwise be spent on a Thunderhawk or a Fellblade.

Pimpin Rides

Also worth mentioning, that Perturabo and Dorn are special enough to get their own personal special/unique vehicle, other primarchs may get their own vehicles in the future (who knows?). However, rules dictate that neither vehicle can be taken in games under 3000 points. Meaning you can only use it in 3000+ matches.

• Perturabo gets to ride in a Shadowsword with the Command Tank upgrade. Not only that, but Perturabo is so awesome, he managed to somehow give it 15 troop capacity, meaning it can take 12 Power Armoured dudes + himself, or 6 Terminators for his bodyguard. But, it doesn't stop there! It also has a single Void Shield! It costs 25pts more than a normal Shadowsword with the same upgrades, but strictly speaking it does NOT have BS4 unless you take the targeter sponsons as the Legion Crew upgrade is not mentioned (the command tank upgrade is), but it's so awesome, who cares? It's called the Tormentor.
• Dorn, on the other hand, gets a customised Thunderhawk Gunship, the Ætos Dios. This ship has Turbo Laser as standard, plus a single Void Shield to protect it, it also has It Will Not Die so can regenerate some of its hull points and finally it ALSO has a 4+ invulnerable save against missiles, all on top of being a flyer which means you can only snap-shot at it, all for the bargain cost of 600 points - which is actually 175 points CHEAPER than a normal Legion Thunderhawk with a Turbo-Laser.

Douchebagginess

It is well known that most of the primarchs were douchebags to varying degrees.

From least to most douchebag. Note, the scale really drops off into fucking douchebag after Jaghatai.

1. Vulkan - The least douchebaggy primarch by far. Vulkan routinely put the life of him and his men on the line for the sake of the Imperial citizens. A total bro. Also was the largest, strongest Primarch (Ferrus' metal arms were determined as cheating) and held back in sparring for fear of hurting his brothers. His only real fault was that, despite his strong distaste for terror weapons, he had a thing for setting people on fire.
2. Sanguinius - Despite some... unorthodox tendencies, he is reported as being the most charismatic of the primarchs, perhaps second only to Horus. A pretty all-round nice guy.
3. Magnus the Red - Before the whole Prospero thing, this guy's MO was all about the advancement of humanity, happily taking remembrancers along his legion (Although all remembrancers amongst the fellowship were psykers to some degree). Magnus was a friendly and open-minded idealist, which makes it all the more tragic when he gets deceived, framed, backstabbed and then coaxed into selling his soul to the Cuttlefish of Keikaku. He is easily the most sympathetic of the traitors, considering he only joined them after being backed into a corner; had Jaghatai been at his side during and post Nikea (especially considering he knew about the webway project), things might have turned out differently. He was also the only traitor primarch who actually cared about his men, even after ascending to daemonhood. The novel Deathfire also ups his bro-ness quite a bit, as he proved himself the only traitor-aligned Primarch to sincerely do something very helpful for one of his loyalist brothers after the Horus Heresy was already in full swing. This "special favour" is made all the more striking given how it took place after Magnus had his adoptive homeworld burned out from under him. Perhaps his skin was red not only because of mutation, but because it also showed the greatness of his heart?
4. Corax - Even after being raised under the tyranny of the Kiavahrans, he refused to take after their tyrannous ways, wanted to make things right, and asked the Emperor to end the civil war he started while liberating his homeworld of Lycaeus. Seeing the ruthless tendencies the Terran members of his legion had, he quietly shipped them way the fuck away from the rest of the Great Crusade to go fight xenos or had them all slaughtered during the Battle of Gate 42. One of the only primarchs to readily admit his own mistakes, which were many and sometimes tragic.
5. Jaghatai Khan - Despite him being modeled after the guy who holds the high score on raping and pillaging, Jaghatai was actually very reasonably and a pretty fun guy to be around. His main hobbies included raiding and hoverbikes, but he had an appreciation for the fine arts as well. He was very good friends with Magnus and very pro-psyker. However he also kept distance from pretty much everyone else, save Horus, not wanting to deal with other people's bullshit, unless they are really worth the effort - as the result very few people knew and trusted him (especially once his only bros turned traitor). While the Khan didn't seem to care too much about the whole Great Crusade thing and spent most of his time doing his own thing, he never turned his back on the Imperium.
6. Horus - Pre-heresy he was a surprisingly chill dude, except if you crossed his sensibilities. Got along well with the regular people and his brothers, but he gradually started treating some of them like shit after becoming Warmaster. He may have also been tricked into joining Chaos when he received a vision of the Imperium 10,000 years into the future where the Emperor was worshiped as a god and everything was Grimdark--a future that, unbeknownst to him, he would help to create. The whole heresy thing just sort-of kills his position on the list. Also a dick to some remembrancers.
7. Ferrus Manus - A big dude with a penchant for bursts of choleric anger. Tended to scare people off due to his brutal ideals and constant resting bitch face. Surprisingly, Ferrus wasn't so bad after you got to know him, and treated his legion and his closer brothers with great respect. Also saw his legion's metal-over-flesh fetish as, well, a cancerous fetish, and wanted to eventually purge that out, but his plans got put on hold due to inconvenient head loss.
8. Rogal Dorn - Although one hell of a masochist, and at times thick-headed, he did see the idea behind the Imperium, and actually somewhat agreed with it. Honest and dependable, while Rogal didn't make for interesting conversation, he would always do his job without complaint. Had as much empathy and subtlety as a brick and ended up hurting a lot of people (mostly emotionally, but sometimes physically too) with his over-the-top brutal honesty. The prime example was when he betrayed Fulgrim's trust after they had a discussion regarding Konrad's visions, and provoked Curze into slashing him across the face.
9. Guilliman - Eurgh. This dude was a statesman in the same way as Atatürk. Great at building states, if you ignore all the deported and murdered people who didn't agree 100% with the new regime. Not an outright bastard, but insufferably arrogant. Rowboat constantly spoke and behaved like he knew what was best for everyone. Yet despite what some people would have you believe, he knew he couldn't plan for every situation and expected people to use their own judgment rather than blindly follow his codex.
10. Lion - A secretive dude who nobody really knows what the fuck is up with. Even his own men didn't know what was up, with some of the Fallen Angels believing that he delayed going to Terra to see which side would win the battle. Had some strange ideas about how to handle the whole heresy thing. Civilized his planet by making it into a hive world ruled by Terran nobles. The Lion is a weirdly inconsistent guy, being honorable while at the same time being unreasonably petty and prone to fits of anger. Probably bipolar.
11. Alpharius Omegon - Damned if anyone knows. You just can't trust that/those guy(s), which does make him/them a pretty big dick by default.
12. Fulgrim - Not as much a dick as some other primarchs. Still a dick to humans and marines who didn't match his ridiculous high standards. He also can't keep a secret, betraying Konrad Curze's trust and causing him to go nuts on Dorn's face. Other than Horus and Sanguinius, was the only Primarch to really get along with all his brothers (save Jagatai, but that's his fault), and was BFFs with Ferrus Manus, of all people. That is, until he chopped his head off. Rude. Also took pride to the extremity of arrogance, hence his fall to Slaanesh.
13. Mortarion - Rubbed everyone the wrong way. EVERYONE. Didn't very much care about collateral damage or leaving the planet in any kind of civilized state afterwards. He was also notorious for using chemical and radiological terror weapons and generally not giving a fuck about who got killed by them. Mortarion was just a sour bastard that nobody made any attempt to get close to, probably because he smelled so fucking bad. Still not a big a douche as the next person on our list.
14. Leman Russ - The most douchebaggy loyalist primarch. Overreacted ever so slightly at Prospero. Left very little when he invaded a planet who had turned down the Imperium's lenient offer of willing compliance. Took no truces and gave no fucks. At all. He didn't even feel bad when he found out he was playing into Horus' hands by killing the Thousand Suns because they were all a bunch of dirty psykers who deserved to die anyway. Also, either he's a hypocrite or in massive denial, as his own Wolf Priests are basically psykers as well. Only seemed to hit it off with Corax, mainly due to their job descriptions being the same, albeit with very different approaches.
15. Angron - Loved killing people and not much else. Most of the casualties within his legion were a result of him being a team-killing psycho because quite frankly he didn't care what he got to kill as long as he got to kill it. That said, Angron at least had an excuse for being such a rampaging dick all the time. The butcher's nails had effectively turned him into a half-mindless killing machine. On top of that, he got fucked over pretty hard by Big E when they first met, so it's no wonder he went traitor the moment Horus made him an offer. At the end of the day, Angron was probably the primarch who gave least fucks about his legion, although he never really wanted one to begin with. He also put butcher's nails into some of their skulls, which is a pretty fucked up thing for him to condone.
16. Perturabo - Cares even less about the life of his legionaries and civilians than Mortarion. Killed 10% of his legion when he assumed command. Unlike other primarchs like Angron and Mortarion, Perturabo didn't even have a tragic upbringing to justify his shitty personality. He was just an envious, petty bastard who was always complaining whenever things didn't go his way (which was always).
17. Konrad Curze - Arguably the most sadistic of all primarchs, Konrad really got off to torturing people and manipulating the masses through fear. Warped as it may have been, he did at least have a sense of justice. Unfortunately, his desire to protect the innocent was eviscerated and left to die in a gutter by his desire to punish the guilty. Any ideas of mercy or decency he may have harbored had been long buried under a massive pile of flayed guts. He did finally admit that what he had done was wrong, but instead of trying to atone for his atrocities, he just let himself get killed. Lame.
18. Lorgar - The dude who brought this whole fucking mess into fruition. If only he had strangled Erebus at the first mention of chaos. Instead he decided he was going to ruin everything for everybody because nobody was on board with his kooky cult shit. Lorgar is why we can't have nice things.

See Also

Return of the Primarchs: A What IF? series filled with pure AWESOME and MANLY TEARS.

A little side note, if you want an awesome look at the Primarchs in all their Crusadey goodness, go look at Aerion the Faithful's Libris Primaris project. http://www.bolterandchainsword.com/topic/152862-artwork-libris-primaris/

Gallery

Loyal

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  Lion El'Jonson

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  Jaghatai Khan (look at those high-heeled boots)

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  Leman Russ

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  Rogal Dorn

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  Sanguinius

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  Ferrus Manus

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  Roboute Guilliman (Big Bobby G)

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  Vulkan

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  Corvus Corax

Traitor

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  Horus Lupercal (THAT ONE FUCK-UP)

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  Fulgrim (look at his sexyness)

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  Perturabo

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  Konrad Curze/Night Haunter/ Batman

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  Angron (GETS. SHIT. DONE.)

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  Mortarion

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  Magnus the Red/psyker

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  Lorgar Aurelian (goldboy)

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  Alpharius/Omegon/everyone

The Primarchs of the Space Marine Legions
Loyalist Corvus Corax - Ferrus Manus - Jaghatai Khan Leman Russ - Lion El'Jonson - Roboute Guilliman Rogal Dorn - Sanguinius - Vulkan
Traitor Alpharius/Omegon - Angron - Fulgrim Horus - Konrad Curze/Night Haunter - Lorgar Magnus the Red - Mortarion - Perturabo