Leonard Caston Jr. (born November 13, 1943) is an American rhythm and blues songwriter, record producer, pianist and singer. He recorded for both the Chess and Motown labels in the 1960s and 1970s, and co-wrote or co-produced several major hit records, including Mitty Collier's "I Had A Talk With My Man" (1964), The Supremes' "Nathan Jones" (1971), and Eddie Kendricks' "Keep On Truckin'" (1973) and "Boogie Down" (1974).
Caston was born in Chicago, the son of blues musician Leonard "Baby Doo" Caston. After spending some time in the US Army, in 1964 he joined Maurice McAlister, a fellow member of the Greater Harvest Church, in his vocal group, The Radiants. The group recorded for the Chess label (for whom Caston's father also recorded), and while working at the label Caston co-wrote, with Billy Davis, new words for James Cleveland's gospel song, "I Had A Talk With God Last Night". Recorded by Mitty Collier with secular lyrics as "I Had A Talk With My Man", it became a hit single (no. 41 on the Billboard Hot 100) in late 1964. Caston left the Radiants in 1965, after their first two hit singles, "Voice Your Choice" and "It Ain't No Big Thing", and began working as a session musician, songwriter and producer at Chess. He played piano on Fontella Bass' hit "Rescue Me", and also worked with singers Bobby McClure, Jan Bradley and Laura Lee. He returned to work with the Radiants in 1967, writing and producing their final hit, "Hold On".