Spider-God

Possibly a depiction of the Spider-god, or a stylized Arachnarok Spider (which it probably looks like anyway) from the 8e Army Book.

The Spider-God (AKA the Feaster From Beyond and The Scuttling Queen) is a deity from Warhammer Fantasy and its sequel-setting Age of Sigmar. As you can probably tell from the name, it is the god of Spiders worshiped by Forest Goblins in the Old World and the Spiderfang Grots of the mortal realms - although most other factions think that it's just a myth, and that they're all too high off of spider venom to know it.

Origins

Canon information on the Spider-God is scarce, since it was only introduced in 7th edition and the Forest Goblins had never been prominent. The Spider-God's origins in the Old World are a mystery, but it was apparently content to reside in the Warp, doing who knows what and being worshiped by nobody in particular. In the Mortal Realms, its worshippers believe that the it was a spider that (as most Destruction creation myths go) bit Gorkamorka's toe as he was rampaging through the Mortal Realms. In doing so, it became infused with the god's power, becoming an aspect of the god that the Spiderfang Grots worship. It is currently unknown if this Spider-God is even technically the same entity that existed in the World-That-Was. If it is, then the this may explain where it got its power from.

Warhammer Fantasy

In the wet, wild, and wolly days of the Warhammer World, the Greenskins migrated across the world and mostly settled in the Badlands (AKA Warhammer Eurasia). A particular bunch of Goblins entered the woodlands of the Drakwald - essentially the Black Forest of Warhammer situated in future Empire territory. These Goblins found the forest to be mostly inhabited by giant Spiders of every size, from 'microscopic mite' to fucking 'four-story castle'. The two initially were at constant war, with the spiders unable to defeat the Goblins, since greenskins release spores upon their death, leading to massive population growth where they are defeated. (although they weren't really trying, just eating what came to them). The Goblins, despite these ludicrous numbers, couldn't defeat the Spiders because... well, they were massive apex predators and the Goblins were stumpy, idiotic spore-apes.

As time went on natural selection took place, and the dumber Goblins gave way to those clever enough to steal the young from their enemies to raise as mounts, as well as those smart enough to figure out which small spiders to eat, and which ones to avoid. The Goblins used sacrifices stolen from Beastmen warbands their kin along with some ritual bloodletting to appease the larger, more undefeatable spiders. Mutations began to manifest amongst the Forest Goblins, resulting in extra arms, eyes, natural venom, and other spider-like traits appearing rarely among their population. Eventually, the Shamans of the Forest Goblins found a way to enter trances similar to those used to channel Gork and Mork (or was it Mork and Gork?) using poisonous spiders, which proceeded to bite and pump their tongues full of venom. This dragged the minds of the Goblins through the Warp and plopped their consciousnesses right before the Spider-god itself. The Spider-god then taught them dances which would prove kinship to the spiders of the world. Why it did so is unknown - perhaps it was simply impressed that these random Goblins tripped so hard that they threw their souls into the Warp, or perhaps it was just bored.

Some Shamans attempted to use these dances to communicate with the Arachnarok Spiders, the biggest and baddest spiders around, that were known for being able to wipe out life in entire swathes of the forest. Predictably, these early attempts were met with the unfortunate Shamans being wrapped up and liquified into a protein snack. But the Shamans kept trying, and continued communing with the Spider-god. They loved it so much that it eventually became the #1 deity of the Forest Goblins with Gork and Mork/Mork and Gork as subordinate gods to its greatness. Effigies of spiders created with skulls adorned the Forest Goblin settlements, which were increasingly relocated to nearby Arachnarok lairs. Given how deeply ingrained into the Greenskin culture the two Gods are, this is no small feat. Eventually the Arachnaroks began accepting the Goblins' sacrifices, and with the dances of the Shamans being echoed by the tribes they eventually began to see the Forest Goblins as their own young, allowing them to crawl all over their bodies and build wooden structures held together with the Arachnarok's own web on their backs. (Note - since we're talking about spiders here, that doesn't mean they won't eat any who get too close to the fangs or ensnared on a web.)

And that's about it, for the Spider-God in the Old World. Since the Forest Goblins weren't deemed important enough to even merit so much of a mention in End Times, the Spider-God's participation was unknown. Stay classy, Geedubs.

Age Of Sigmar

The Spider-God survived into the Age of Sigmar, where it was confirmed that no, the Grots were not just tripping balls - it actually exists! Not only that, but it also exists alongside a pantheon of other greenskin gods that are believed to be aspects of Gork and Mork/Mork and Gork/Gorkamorka. It even has a small following amongst non-Greenskins now, with assassins and other seedy outcasts of society paying tribute to it. Its presence can be felt in the places the Spiderfangs have conquered - usually through an intense case of the jitters and the feeling of many eyes watching you.

The Spider-God has been known to manifest its presence through the spiders that the Spiderfang Grots control, the size of which can vary from a couple of inches wide to the size of dogs and bigger. The Arachnaroks - which are somehow still around - are believed to be its earthly avatars in a way similar to Greater Daemons. This is especially so in a unique species of Arachnarok called the Skitterstrand, which are able to create literal portals to jump between the realms, pop out, and drag some poor unsuspecting soul away with them.

Where do they get dragged, you ask? Well, that's the fun part. Its home is located in Shyish, in an underworld known only as "The Evercrawl". This hell for arachnophobes and heaven for Grots is a place believed to be the afterlife for the children and worshippers of the Spider-God. This is where the Skitterstrands make their home, where they bring the souls of those they kill to be drained entirely dry by their god. Entering this place if you are not a Grot or other Spider-God worshipper is more than a death sentence - it means your immortal soul will soon be digesting in the belly of Shelob's granddaddy. As to why Nagash tolerates its presence in his realm, presumably he's too afraid to go into his basement and chase it off with a skele-broom.

In terms of temperament, the Spider-God is unique. It lacks the chaotic aggression or manic urgings seen in other destruction gods, and has a feral, savage intelligence. Like most spiders, it's a highly patient hunter, biding its time and waiting for the perfect moment to strike out at the realms more directly. How so? Well, the Spiderfangs claim that the Spider-God wishes to spread its influence throughout the realms and thus grow I in power till one day, it can cover all of reality in its godly webbing, thus permanently blotting out all light and ushering in an era of perpetual twilight known as "The Everdank". In this blissful new era, the Spiderfangs and their fellow children of the Spider-God will reign supreme over all reality, devouring everything.

In the meantime, it is believed to be weaving a more short-term web of its own plots, through both its Spiderfang worshippers and even its followers among the other mortal races. Rumour has it that it has even created it’s own binding of Soulbound. It is yet to be confirmed whether this binding includes a wisecracking human with a penchant for red and blue spandex or not.

Gods of Destruction
Bad Moon - Fire Mouth - Gorkamorka (Gork - Mork) - Everwinter - Gulping God - Kragnos - Spider-God