"Shine On You Crazy Diamond" is a nine-part Pink Floyd composition written by David Gilmour, Roger Waters, and Rick Wright. It appeared on Pink Floyd's 1975 album Wish You Were Here.
The song was conceived and written as a tribute and remembrance to their former band member Syd Barrett, a founding member of Pink Floyd.
Barrett was ousted from the band by the other members in 1968 due to his drug use and (partly-related) troubled mental health, which had affected his ability to integrate with the rest of the band and perform and create as a musician. He was replaced by David Gilmour, Barrett's former school friend who had initially been brought in as second guitar. The remaining band members felt guilty for removing him, but they viewed it as necessary, admiring Barrett's creativity and being concerned about his severe mental decline.
Syd Barrett, visiting Abbey Road Studios on 5 June 1975
One day during recording, Barrett (now heavyset, with a completely shaved head and eyebrows) wandered into the studio (although Mason has since stated that he is not entirely certain whether "Shine On You Crazy Diamond" was the particular work being recorded when Barrett was there). Because of his drastically changed appearance, the band did not recognize him for some time. When they eventually determined the withdrawn man in the corner was Barrett, Roger Waters became so distressed about Barrett's appearance he was reduced to tears. Someone asked to play the suite again for Barrett and he said a second playback was not needed when they had just heard it. When asked what he thought of the song, Barrett said it sounded a "bit old".