Will Ferrell tops our list based on the comedic range he displayed during his seven years on the show. Whether he was doing hilarious celebrity impersonations (Alex Trebek, James Lipton, Harry Caray, George W. Bush and Janet Reno, to name a few), creating his own immortal pop culture characters (The Spartan Cheerleaders, The Culps, The Lov-ahs), or elevating a one-time sketch with his straight-man delivery (the "Oops, I Crapped My Pants" spokesperson, a homeless man posing as a nude model, Blue Oyster Cult's cowbell player Gene Frenkle), Ferrell was always at the top of his game. He's also one of the few cast members who consistently kept a straight face during even the most absurd of sketches. And his post-SNL career is nothing to sniff at either. From Anchorman to Zoolander, Ferrell has left an indelible mark on the world of comedy.