Isaac Leffler (7 November 1788-8 March 1866) was a member of the US House of Representatives (NR-VA 18) from 4 March 1827 to 3 March 1829, succeeding Joseph Johnson and preceding Philip Doddridge. Born in Washington County, Pennsylvania, he practiced law in Wheeling, West Virginia before serving in the Virginia House of Delegates from 1817 to 1819, 1823 to 1824, 1825 to 1827, and 1832 to 1833. He later served in Congress, and he moved to Burlington, Iowa in 1835 and became a judge, territorial delegate, and US Marshal there. He died in Chariton, Iowa in 1866.