Nicknamed Papa John, he was the guitarist, singer, and songwriter who fronted the folk band The Mamas & the Papas.
He formed his first doo-wop group while attending Linton Hall Military School in Virginia. His first real band was a folk trio called The Journeymen.
He wrote the musical Man on the Moon in 1975.
He had been married four times and was accused of having an incestuous, non-consensual relationship with one of his daughters for ten years.
He was the father of Mackenzie Phillips.