Who Are You is from the 1978 album of the same name, the last album recorded with drummer Keith Moon, who died a few weeks after its release.
Released as a single, the track reached #14 on the Billboard Hot 100 and became one of The Who's biggest hits.
Years later, a version of the song was chosen as the opening theme of the series CSI: Crime Scene Investigation, which revived the success for new generations and kept the song alive to this day.