| Robert M. Leach | |
| State1: | Massachusetts |
| Term Start1: | November 4, 1924 |
| Term End1: | March 3, 1925 |
| Predecessor1: | William S. Greene |
| Successor1: | Joseph William Martin Jr. |
| Birth Date: | 2 April 1879 |
| Birth Place: | Franklin, New Hampshire |
| Death Place: | Eustis, Florida |
| Nationality: | American |
| Party: | Republican |
| Alma Mater: | Dartmouth College |
| Occupation: | Businessman |
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.