William Moody (born Dec. 23, 1853, Newbury, Mass., U.S.—died July 2, 1917, Haverhill, Mass.) was a U.S. attorney general (1904–06) and associate justice of the U.S. Supreme Court (1906–10).
Moody began practicing law at Haverhill, Mass., in 1878 and became active in local Republican Party affairs. He served as city solicitor (1880–90) and district attorney for eastern Massachusetts (1890–95). He first gained national attention as prosecutor in the sensational murder trial (1893) of Lizzie Borden.
Elected to the U.S. House of Representatives in 1895, he served until 1902, when President Theodore Roosevelt appointed him secretary of the navy and, in 1904, U.S. attorney general. During his two years in the latter post, Moody moved to break up the giant monopolies, notably in the meat-packing industry, through vigorous enforcement of the antitrust laws. In 1906 he was appointed to the Supreme Court by Roosevelt (who had first offered the seat to William Howard Taft). Illness limited Moody’s effectiveness on the bench and forced him to resign after only four years.