John Varnum (25 June 1778-23 July 1836) was a member of the US House of Representatives (NR-MA 3) from 4 March 1825 to 3 March 1831, interrupting Jeremiah Nelson's terms. Born in Dracut, he practiced law in Haverhill before serving in the state senate and Congress. He later moved to Niles, Michigan, where he died in 1836.