Peter Adkison (the founder of WotC and current owner of GenCon) posted here about how Wizards of the Coast got its name:
Here's the story of how Wizards of the Coast got it's name, which of course is intertwined with the story of the inception of the company itself.
My early days of D&D were in the late 70's and early 80's in Walla Walla, Washington. One of the legendary campaigns of the region was a world called Taragarden GM'ed by a guy named Butch Van Dyke. I played in this game from time to time along with a number of friends but the ones who pertain to this story were Terry Campbell, Darrell Judd, and Ken McGlothlen.
One day we were at Darrell's apartment and Terry had just purchased a Judges Guild boxed set called the City State of the Invincible Overlord (or something like that) and we were oo-ing and ah-ing over it when Terry planted the seed of starting a game company someday when he said, "We could start a game company and publish something like this!" And almost immediately Darrell suggested we name the company "Wizards of the Coast" after a mage guild in Butch's campaign that we all thought was really cool. I don't really know why, the name just had a certain panache, partly I'm sure because of how Butch played the guild as quite exclusive, powerful, and sophisticated.
In the space of about 10 minutes we all agreed that it was a great idea to start a game company and call it Wizards of the Coast but that we should probably wait until we finished school. My best guess is that this conversation took place around 1980.
Neither Darrell or Terry took the notion too seriously, but Ken and I did. From time to time we would create something random and put "Wizards of the Coast" on it. I self-published a mass combat system for D&D called "Castles and Conquest" in the early 80's, and Ken put the name on a graphic design he did for a wedding invitation. For the next decade we used the name as if it meant something, and it did to us of course.
In 1990 I was sitting in my cubicle at Boeing typing with Ken on telnet when I typed, "We should start Wizards of the Coast for real." There was a long silence, to which he replied, "You're serious, aren't you?"