The tributes to late night giant David Letterman have already begun even though he won't sign off until sometime next week. The Late Show host announced his upcoming retirement during his show on Thursday. Jimmy Fallon has always been vocal about his admiration for Letterman—after all, he's the one who originally hosted Late Night after The Tonight Show with Johnny Carson.

Last night, Fallon used Letterman's famous "Top Ten" list bit to honor the elder statesman of late night. Check out the clip below: 

[via The Tonight Show]