Marcus Maskell Marsh (1904–1983) was an English racehorse trainer. He was the son of the trainer Richard Marsh. His British Classic wins included the Epsom Derby and St. Leger with Tulyar (1952) and Windsor Lad (1934) as well as the 2,000 Guineas with Palestine (1950). He was British flat racing Champion Trainer in 1952. Marsh's career spanned over forty years until his retirement in 1964 with a break during World War II when he served in the RAF.