A talented actor, best known for playing the recurring role Reginald Barclay, on Star Trek: The Next Generation. He also played the same character in Star Trek: Voyager, and in the movie Star Trek: First Contact. It's one of the more memorable recurring characters, because he's a twit, and also because the character came fairly close to omniscient in the ST:TNG episode The Nth Factor. He's not stupid--I suppose that anyone who gets into Starfleet Academy can't really be a twit--but his demeanour makes him out to be a fool. The character does display some other traits, mostly in the holodeck, which adequately displays some skill on the part of the actor.
A noder points out he was also on The A-Team.