Green Ronin Publishing
Founded in 2000 by a group of game designers including Wizards of the Coast alum Chris Pramas, Green Ronin Publishing is a leading producer of tabletop role-playing games.
Green Ronin has produced numerous third-party supplements for Dungeons & Dragons 3rd Edition under WotC's Open Gaming License, including various Sourcebooks on Asian-themed fantasy; a fresh look at The Multiverse in The Book of the Righteous and The Book of Fiends; the "Mythic Vistas" line, interpreting D&D game rules for various real-world settings (ancient Egypt, the Spanish Main, the Biblical Holy Land, and so on); and the pirate-themed Freeport campaign setting, which they have also released for D&D 4th Edition, Pathfinder, and their own True 20 RPG.
They have also created their own new RPGs based on the d20 system: Blue Rose, a fantasy game designed to emulate the works of authors like Diane Duane, Tamora Pierce, and Mercedes Lackey; True 20, a generic RPG designed to accommodate almost any genre, in the vein of GURPS or D20 Modern; and the critically-acclaimed superhero RPG, Mutants and Masterminds, easily Green Ronin's iconic product line.
Finally, Green Ronin has produced many licensed games, including DC Adventures (using Mutants and Masterminds rules) and RPG adaptations of A Song of Ice and Fire, Dragon Age, and Thieves' World.