Powell St John
Biography
Rayward Powell St. John (September 18, 1940 – August 22, 2021) was an American singer, songwriter, and visual artist, active on the mid-1960s Austin, Texas campus folk/bohemian music scene. He was an occasional member of various Austin rock groups, including St. John the Conqueroo, and wrote some songs for The 13th Floor Elevators, including "Kingdom of Heaven" and "You Don't Know (How Young You Are)", included on the band's 1966 debut, The Psychedelic Sounds of the 13th Floor Elevators. He also was a founding member, along with Tracy Nelson, of the San Francisco-based band Mother Earth.
Bio from Wikipedia