Sidney Willard (September 19, 1780 – December 6, 1856) was an American academic and politician who served in the Massachusetts House of Representatives, on the Massachusetts Governor's Council and as the second Mayor of Cambridge, Massachusetts. Willard was the Librarian of Harvard from 1800 to 1805. From 1807 to 1831 he was the at Harvard College. Willard was elected a Fellow of the American Academy of Arts and Sciences in 1808. Willard was the son of Harvard president Joseph Willard and Mary (Sheafe) Willard.