Stand-up Comedians: Patton Oswalt, by Josh Lynch

I love me some Patton Oswalt. Original sketch here (with speech balloon)

Stand-Up Comedians: Rodney Dangerfield by Rich Flood

Stand-Up Comedians: Reggie Watts by Eric Schuster

 

Reggie Watts is the man.  Almost everything he does is improvised, looping his beatboxing with silly phrases and sound effects to make some remarkable songs.  He's kind of hard to explain, so here's him derpin' around, doing what he does best: