Marcus Maskell Marsh (1904–1983) was an English racehorse trainer.

His British Classic wins included The Derby and St. Leger with Tulyar (1952) and Windsor Lad (1934) as well as the 2,000 Guineas with Palestine (1950).

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.

On 28 September 1936 he married tennis player Eileen Bennett.

This British horse racing biographical article is a stub.