For many years there has been a legend about Warcraft, that the first game of one of the best money-making machines franchises was in fact going to be originally the computer version of Warhammer, by Games Workshop.
Stories say that GW decided to cancel it (or decided to not do it) but Blizzard went on and released Warcraft: Orcs & Humans.
I've tried many times to hunt for reliable sources about this, not finding a single non-forum based comment/version/claim.
Well, today, reading a spanish PDF e-zine (Cargad! #10) I found an interview with Félix Paniagua, an ex-GW miniatures scuptor that claims the following (fragment on page 22):
Felix: [...] Did you knew that Warcraft was going to be Warhammer?
Interviewer: What?
Felix: The guys at Blizzard proposed Games Workshop to do a computer game based on Warhammer. Games Workshop said no, so Blizzard still continued with it and called it Warcraft. Games Workshop didn't took long to start being sorry [for the decision they took].
 
So, for me an ex-employee's claim is enough proof that this is actually true.