Chaosium
Chaosium was first founded by Greg Stafford in 1975 to publish his own fantasy wargames, then published RuneQuest in 1978. Its first major success, though, was Call of Cthulhu in 1981, an investigative game of eldritch horror based on Chaosium's Basic Role-Playing rules and H.P. Lovecraft's Cthulhu mythos. Chaosium produced both original and licensed RPGs throughout the 80s and 90s before effectively splitting up the company just before the turn of the millennium. Chaosium founder Greg Stafford and Call of Cthulhu designer Sandy Petersen both returned to active roles in the company in 2015 to finish the 7th edition of Call of Cthulhu, resulting in a revitalization of the company and critical success for the game. Today, Chaosium continues to support Call of Cthulhu in addition to a number of other original and licensed games.