Later Edit: Randy's officially only the 15th pitcher to throw a perfect game. Unofficially, you have Harvey Haddix's 12-inning perfecto that he lost in the 13th to the Milwaukee Braves.
And, here's a thought: the last pitcher in the National League to throw a perfect game was Dennis Martinez of the Montreal Expos. Randy Johnson started his career with Montreal, and Dennis Martinez ended his career with Atlanta. Strange how those things work out, isn't it?