03/20/2012 01:50 pm ET Updated May 10, 2012

Late Night Crossovers: Late Night Hosts On Each Others' Shows (VIDEO)

With so many great late night shows on television, it can be hard to keep up with all of them. Thankfully, once in awhile, our favorite hosts drop by each others' shows for a sketch, an interview or, in some cases, an all-out late night brawl.

Most of the appearances are just for fun, like the "feud" between Jimmy Fallon and Stephen Colbert over their Ben & Jerry's ice cream flavors. Some of the crossovers, however, become significant moments in late night TV history, such as David Letterman doing an interview with Johnny Carson after not becoming the next "Tonight Show" host and Conan O'Brien's return to his old "Late Night" studio after his very messy parting from NBC.

Whatever the reason, when different hosts collaborate, something interesting always happens. We collected some of our favorite late night crossovers from the last few decades. Don't forget to vote on the best crossover moment!

Late Night TV Host Crossovers