Aaron Harlan (September 8, 1802 – January 8, 1868) was a U.S. Representative from Ohio, cousin of Andrew Jackson Harlan.Born in Warren County, Ohio, Harlan attended a public school, and later attended a law school. He was admitted to the bar and began practice in Xenia, Ohio, in 1825. He served as member of the Ohio House of Representatives in 1832 and 1833, and he served in the Ohio Senate in 1838, 1839, and 1849.