Jon Stewart vs. Stephen Colbert
This one's more of a mock rivalry, but that doesn't make it any less entertaining. Stewart and Colbert have been hilarious foils to each other ever since The Colbert Report launched in 2005. For every Stewartian "Rally to Restore Sanity," there will be a Colbertian "March to Keep Fear Alive." Indeed, Colbert intensified the rivalry a few weeks back by breaking The Daily Show's 10-year winning streak at the Emmys. The truth is that they're good friends, but the truthiness? That's another story.