Rex A. Garvin (July 24, 1940 – December 2, 2013) was an American rhythm and blues singer, songwriter, keyboard player and arranger. His writing credits include the 1957 US chart hit "Over The Mountain, Across The Sea", by Johnnie and Joe, and his own 1966 recording "Sock It To 'Em J.B.", later recorded by The Specials.
He was born in New York City and raised by foster parents in the Bronx. He took piano lessons as a child. In 1954, he helped form The Hearts, a female vocal group with whom he sang bass, played piano and wrote and arranged songs. Managed by neighbour Zelma "Zell" Sanders, The Hearts' first record, "Lonely Nights", was issued on the Baton label in early 1955 and reached # 8 on the Billboard R&B chart. Garvin remained involved with the group as their pianist, arranger, musical director and (in their own word) "maestro" through various personnel changes during the 1950s, later explaining that he did so "mainly to meet girls". Members of The Hearts later performed as The Jaynetts.