The chat equivalent of Ali vs Foreman: David Letterman's temperamental genius against blue-collar slugger Jay Leno. Leno landed NBC's coveted Tonight Show ahead of Letterman in 1992, forcing the latter to jump ship to CBS. The two former pals subsequently fell out as they both battled for ratings dominance. But maybe all has been forgiven: the rumour is Leno will be one of Letterman's final guests before the great man retires this year. And they got together in 2010 for this Super Bowl ad.
Conan O'Brien took over Leno's The Tonight Show in 2009 (it had been planned for five years) only for Leno to return, taking the slot an hour before in NBC's schedules with derided The Jay Leno Show which hurt Conan's ratings. Conan decided to bow out – but not before some inspired sketches and a heartfelt farewell speech.
Oh, Jay. You again? At the height of the Conan controversy Leno agreed to let rival host Jimmy Kimmel on his show via video link. To say Kimmel – pro-Conan to the hilt – demolished Leno would be an understatement. Leno later explained there was a reason he didn't retaliate: "Rich people whining and complaining? Shut up."
The famed US TV writer Bill Carter has written two barnstorming books about the late night US chat show wars. In Britain, you'd struggle to fill a pamphlet. Jonathan Ross called Graham Norton a "d*ck" on Twitter for saying he didn't know who the other nominees were after his British Comedy Award win last year. But that's pretty much it.