Armistead Thomson Mason (August 4, 1787 – February 6, 1819), the son of Stevens Thomson Mason, was a U.S.
Senator from Virginia from 1816 to 1817.
Mason was also the second-youngest person to ever serve in the US Senate, at the age of 28 and 5 months, even though the age of requirement for the US Senate in the constitution is 30 years old.