Chaosium Inc. ( kay-OSS-ee-əm) is a publisher of tabletop role-playing games established by Greg Stafford in 1975. Chaosium's major titles include Call of Cthulhu, based on the horror fiction stories of H. P. Lovecraft, RuneQuest Glorantha, Pendragon, based on Thomas Mallory's Le Morte d'Arthur, and 7th Sea, "swashbuckling and sorcery" set in a fantasy 17th century Europe. Many of Chaosium's product lines are based upon literary sources.
https://en.wikipedia.org/wiki/Chaosium