William M. Butler (January 29, 1861-March 29, 1937) was a lawyer and legislator for the State of Massachusetts, as well as a United States Senator.
Butler was born in New Bedford, Massachusetts where he attended the public school and studied law. He was admitted to the State bar in 1883. After graduating from the law department of Boston University in 1884, he practiced law in New Bedford until 1895. He was a member of the State house of representatives from 1890 to 1891, and a member of the State senate from 1892 to 1895, serving as its president in 1894 and 1895.
Butler moved to Boston in 1895, and continued the practice of law until 1912, when he engaged in the manufacture of cotton goods. He was a member of the commission to revise the statutes of Massachusetts from 1896 to 1900, and was chairman of the Republican National Committee in 1924.
On November 13, 1924, Butler was appointed as a Republican to the United States Senate to fill the vacancy caused by the death of Henry Cabot Lodge, and served from November 13, 1924, to December 6, 1926, when a successor was elected. His bid for election to fill the vacancy was unsuccessful.
Butler served as chairman of the Committee on Patents (Sixty-ninth Congress), and then resumed his manufacturing interests. He thereafter resided in Boston until his death, and was interred in in Forest Hills Cemetery.