David Letterman & Jay Leno
When Johnny Carson announced he was leaving NBC 's "The Tonight Show" in 1992, fans believed the obvious replacement would be David Letterman, who hosted "Late Night With David Letterman" on the same network. But instead, NBC gave the show to Jay Leno, a comic who had appeared as a guest on Letterman's show multiple times. The bad blood was clear after Letterman delivered the backhanded compliment that Leno was one of the funniest and simultaneously most insecure people he knew.