James Corden picked up Chris Martin on his way to the Super Bowl for another round of Carpool Karaoke, Jimmy Kimmel brought together the cast of "E.R." including George Clooney, and Stephen Colbert gives his best recap of the Iowa Caucuses winners.
During a taping of tonight's 'Late Show', host David Letterman announced to a shocked studio audience that he would be retiring in 2015 after his latest contract ends.