Tommy Chong, from the famous pot smoking comedy duo Cheech and Chong. Epic beard. He probably grew it so people would pay attention to its awesomeness and not notice that he was high all the time.
Zach Galifianakis, other than having a ridiculous last name, has a sweet-ass-beard. While I was checking out The Hangover, I did a double take when I saw Zach's beard. I haven't seen the movie yet, but that beard is quite convincing. I just might dish out the 12 bucks or whatever ridiculous price it these days.
Russell Brand. Some might call him a "comedian" but I really don't find him too funny. However he has a nice beard which would look even better if he tried showering at least once a week.