i think leo dicaprio is gonna be a helluva director one day. after all the shit he musta learneds from scorsesee...

I figured someone would have named Woody Allen. I can't stand his acting schtick and I dislike most of his movies, but I figured he'd get a mention. Annie Hall seems to generally be considered a classic.

Yeah, Allen's a pretty great choice

Ron Howard is neither a great director nor a great actor, but he has solid entries as both.

Genius director. Great actor? Ehh...I loved his role in Sunset Blvd. though.

Hence the "possibly". The director aspect is a given, while the actor one is debatable, however, his performances in Sunset Blvd., La Grande Illusion, The Wedding March and a few others at the very least qualify him for consideration in that area as well - especially upon seeing some of the other persons mentioned in this thread, some of which haven't even had anything you could call "careers", let alone consistent ones, in both fields.