John Varnum (June 25, 1778 – July 23, 1836) was a United States representative from Massachusetts. He was born in Dracut on June 25, 1778. He graduated from Harvard University in 1798, studied law, was admitted to the bar and commenced practice in Haverhill. Varnum was elected as a Federalist to the Massachusetts State Senate. He moved to Lowell. Varnum was elected to the Nineteenth, Twentieth, and Twenty-first Congresses (March 4, 1825 – March 3, 1831) and later moved to Niles in the Michigan Territory where he died July 23, 1836. His interment was in Silverbrook Cemetery.