3. William Shatner
Worst Performances: Kingdom Of The Spiders (1977), Star Trek III: The Search For Spock (1984), Star Trek IV: The Voyage Home (1986)
Ladies and gentleman, say hello to the king of overacting. Seriously, his hammy ways know no equal. The former Captain Kirk has made a living out of exaggerating casual dialogue and ridiculously using his hands to emphasize words, an unnecessarily theatrical approach to acting that's turned him into a punchline amongst pop culture junkies. Ask any good comedian: The best jokes are always rooted in fact.