Moses Mason Jr. (2 June 1789-25 June 1866) was a member of the US House of Representatives (D-ME 5) from 4 March 1833 to 3 March 1837, succeeding Cornelius Holland and preceding Timothy J. Carter. Born in Dublin, New Hampshire, he was raised in Bethel, Maine and served as its postmaster from 1815 to 1833, as justice of the peace from 1821 to 1866, as county commissioner from 1831 to 1834, and in Congress.