Tommy Gavin from Rescue Me isn't one of the funniest guys, but the dude who played him certainly is. A long-time stand-up comic, Denis Leary has always wanted to make the audience squirm. But it's not just his jokes that have earned Leary negative attention. See, Leary was good friends with another comedian on this list, Bill Hicks, until Leary's comedy album, No Cure for Cancer, was released in 1993. The release destroyed their friendship, as it was widely believed that Leary had stolen his material and overall stage persona from Hicks.
More recently, in 2011, Leary released a parody video of “A Charlie Brown Christmas” that found the iconic character converting to Islam and constructing a faulty bomb.