Chaos Gods
The four gods which rule over the Realm of Chaos in Warhammer Fantasy Battles and the Warp in Warhammer 40,000. They love nothing so much as dicking with each other, except perhaps dicking with their mortal followers. Each one is formed by the emotions clumped together in the Warp/Realm of Chaos. For the most part, they represent "bad" emotions, but that also have "good" virtues. They are:
- Khorne: BLOOD FOR THE BLOOD GOD! SKULLS FOR THE SKULL THRONE! MILK FOR THE KHORNE FLAKES! Oh, sorry. In case it wasn't obvious, Khorne is the god of battle, martial honor, and oh yeah, BLOOD! Although primarily formed from hate and rage, bravery and honor are also thrown in the mix.
- Nurgle: The god of filth, pestilence, decay, and generally being a cool dude. Formed from despair and fear of death, acceptance and stoicism are also included. Nurgle is also notable for being the only Chaos god that cares for his followers whatsoever, bordering on love (in fact, in 40k, he loves the Eldar goddess Isha so much that he chained her up and force feeds her his new diseases... yeah, love sucks sometimes).
- Slaanesh: The god of pain, pleasure, and perfection... or in other words, a god of emotions formed from emotions, not all of which are bad. Formed mainly from hedonism and excess, love and creativity are also attributes of Slaanesh. In 40k, the Eldar created him/her by having so many damn orgies they tore a hole in space. I shit thee not.
- Tzeentch: The god of progress, knowledge, Just as planned, and magic. Tzeentch is formed from paranoia and plotting, but also hope and ambition.
The Other Ones
Older editions of Warhammer Fantasy and 40k mention several lesser Chaos gods. Nowadays, they only appear in WFB (and even then, only sparingly), with some (the Horned Rat and Hashut in particular) generally considered to be separate from the "main" Chaos pantheon. These include:
- Be'Lakor: A fallen Chaos champion, who was apparently so crazy powerful that becoming a daemon prince was a demotion. Somehow still able to grant his followers unique magic powers.
- Hashut: Father of darkness and god of the Chaos Dwarves. And if his followers are any indication, god of penis-compensating hats.
- The Horned Rat: Patron of the Skaven, and god of...well, rats. Also disease, mutations, etc., but mostly rats. The Horned Rat once appeared in material form; he's the only Chaos god to do so. Of course, he just started eating a ton of the Skaven present, but still.
- Malal: Renegade Chaos god. Interbutt lore states that he is the god of fractiousness and dissent, which, given the company he keeps, makes him a tad redundant.
- Zuvassin: A minor god who just likes to see shit fall apart, specifically nonphysical stuff like schemes and lives. He and Malal are the co-chairs and so far only members of the Useless-Ass Gods Club (Necoho would join the club, but he doesn't believe it exists).
- Necoho: The god of atheism. I wish I was making that up.
- Mo'rcck, Phraz-Etar, and Ans'l: Puns on the last names of sci-fi and fantasy author Michael Moorcock (who wrote a lot about conflicts between Law and Chaos), artist Frank Frazetta (who drew a lot of movie and comic book posters, especially in sci-fi and fantasy), and Citadel Miniatures founder Bryan Ansell (who also wrote several of the First Edition rulebooks). These guys helped set the tone of the early Warhammer 40,000 universe (purposefully or not), including the propensity of putting spikes on Chaos things, and so they were homaged in the (initial) Third Edition Codex: Chaos Space Marines, which mentioned that Chaos Space Marines often put "spiky bits" on their armour in praise of these three gods. They were never mentioned anywhere else.