One (Harry Nilsson song)

"One" is a song by Harry Nilsson, famous for its opening line "One is the loneliest number that you'll ever do." In 1969, rock band Three Dog Night covered the song on their debut album.

The Muppets and Jimmy Fallon performed an impromptu rendition of the song on the set of Late Night with Jimmy Fallon while rehearsing for the 2009 Christmas performance of The 12 Days of Christmas. Footage of the performance was posted on the Late Night website and Hulu.com in January 2010.