"One After 909" (sometimes titled "The One After 909" in early recordings) is a song by the English rock band the Beatles from their 1970 album "Let It Be". It was written by John Lennon, with input from Paul McCartney, and was credited to their joint partnership. The album version is the live performance from the rooftop concert which took place on 30 January 1969. This performance is also included in the "Let It Be" film. The song was written no later than spring 1960 and perhaps as early as 1957, and is one of the first Lennon–McCartney compositions. "One After 909" is perhaps more reminiscent of early American rock 'n' roll than any of the other songs from the rooftop show, and as a joke for the rooftop chatter, Lennon sings a variant on the opening line of "Danny Boy" after the song is finished.