Chaosium publishes Call of Chtulhu, Pendragon, Elric, and Nephilim. They used to publish Runequest.

Call of Chtulhu is a horror genre RPG set in the worlds of H.P. Lovecraft.

Dragon Lords of Melnibone is an adventure RPG set in the worlds of Michael Moorcock and Elric of Melnibone.

Stormbringer is a d20 adventure RPG set in the same world as DLM.