John Weston Allen (April 19, 1872 – January 1, 1942 ) was an American politician who served as a member of the Massachusetts House of Representatives from 1915 to 1918 and as Massachusetts Attorney General from 1920 to 1923. As Attorney General, Allen was aggressive in his pursuit of white collar criminals. During his tenure, Allen prosecuted Thomas W. Lawson, L. C. Van Riper, and Charles Ponzi. Instead of seeking reelection, Allen ran for Governor of Massachusetts in 1922 but lost the Republican primary election to incumbent Channing H. Cox. Allen served as a member of the United States Attorney General's National Crime Commission from 1926 to 1936 and was the commission's chairman from 1930 to 1936.