Hipgnosis / Storm Thorgerson, 1973. Prism splitting white light into a spectrum. Most reproduced album cover of all time.
From Wikipedia
The discography of the English rock group Pink Floyd consists of 15 studio albums, seven live albums, 18 compilation albums, 11 box sets, three EPs, and 27 singles. Formed in 1965, Pink Floyd earned recognition for their psychedelic or space rock music, and, later, their progressive rock music. The group have sold over 250 million records worldwide, including 75 million in the United States.