Good Will Hunting

Robin Williams, 57: Williams exploded into America's pop-culture consciousness with the '70s TV hit "Mork & Mindy," really just a showcase for Williams' own hyper stream-of-consciousness delivery. His stand-up shows and film roles like "Good Morning, Vietnam" cemented his ... moreposition in American comedy. Though he's gone on to more serious or sentimental roles (loved "Good Will Hunting"; "Patch Adams," not so much), Williams is still firing on all cylinders in impromptu comedy. His recent appearance with David Letterman consisted of Williams' poking fun in a hundred ways at Letterman's "solidarity beard" grown for the writers' strike. Best bit: Williams' impersonation of Letterman as Robert E. Lee. "Suh."