Ed Greenwood
Ed Greenwood is a Canadian fantasy writer and librarian. He's most famous for creating the Forgotten Realms setting for D&D, which as of 5e is the default campaign world. He apparently sold the setting to TSR for a token fee in the 80s- which has got to sting now that toy-and-game goliath Hasbro are rinsing it for all it's worth, and other authors are churning out books in the setting that are way more popular than his own...but due to contract reasons Hasbro is forced to give him the last word on everything in the setting because they forfeit all control over it if they don't.
He's written a shit-tonne of books, often involving his self-insert not-Gandalf called Elminster.