2. David Letterman
The overwhelming flood of tributes to David Letterman is proof that he is one of the most beloved figures in the history of television. His accomplishments don't need to be repeated for the umpteenth time, but suffice it to say that he ushered in an entirely new form of comedy. To comedians of a certain age, watching Letterman in the 1980s was like being a young musician and listening to the Beatles. He gave them the tools to work with, and it's impossible to imagine the modern-day scene without him. Jay Leno may have gotten better ratings, but there's a reason he doesn't appear anywhere on this list. In the end, Dave won the late night war. It wasn't even close.