Robert Milton Leach (April 2, 1879 – February 18, 1952) was a United States Representative from Massachusetts. He was born in Franklin, New Hampshire on April 2, 1879. He attended the public schools, Phillips Academy and Dartmouth College. He moved to Taunton, Massachusetts in 1900 and engaged in the chain-store furniture business in New England.
He was commissioned as captain in the Ordnance Division of the United States Army during World War I. He was elected as a Republican to the Sixty-eighth Congress to fill the vacancy caused by the death of William S. Greene and served from November 4, 1924 to March 3, 1925. He was not a candidate for renomination. He resumed his former business activities and died in Eustis, Florida on February 18, 1952. His interment was in Franklin Cemetery in Franklin, N.H.