Thieves' World was a series of fantasy books featuring short stories by different authors. All were set in the city of Sanctuary, a den of iniquity. They were gritty fantasy long before Game of Thrones. Their were a dozen books published in the eighties, as well as a number of spin off novels and novels by the authors featuring their own characters. Then the series was restarted in a few years ago with new authors.http://en.wikipedia.org/wiki/Theives_World
There was a RPG boxed set published by Chaosium which featured stats for many, many RPG games.
More recently Green Ronin did a d20 version.