Pagan Publishing: 1990-Present
appelcline Though a licensee of Chaosium, Pagan may have been the most notable publisher for Call of Cthulhu in the 90s.
Green Knight: 1998-2002
Green Knight inherited Pendragon from Chaosium, but their publication was short-lived.
Issaries: 1998-2006
Issaries inherited the Gloranthan rights from Chaosium, but didn't hold them for long.
Chaosium: 1975-Present
Chaosium originally followed TSR with a war game, White Bear & Red Moon. It introduced the world of Glorantha, which would be better known through RuneQuest.
Paizo Publishing: 2002-Present
By July, 2002 Stevens had formed Paizo Publishing to take advantage of licenses to Dragon and Dungeon magazines.
Wizards of the Coast: 1990-Present
Wizards of the Coast is, without a doubt, now the big dog in the world of roleplaying. However, they were very much a small fish back in 1990.
What is a Brief History of Game?
Designers & Dragons came out of a simple question, "What ever happened to Imperium Games?"