25. 'Head' (1968)
The Monkees' psychedelic fantasy bombed at the box office, and nobody on earth has ever figured out the plot. Yet it remains a trippy cult classic, with cameos from Frank Zappa and co-writer Jack Nicholson. The music soars from Mike Nesmith's hard-riffing "Circle Sky" to "As We Go Along," one of Carole King's loveliest ballads. Head begins and ends with the grandiose melancholy of "Porpoise Song," the kind of music that can make even Don Draper want to curl up on a couch and cry.