Mordecai Bartley (December 16, 1783 - October 10, 1870) was a Whig politician from Ohio. He served as the 18th Governor of Ohio. Bartley succeeded his son, Thomas W. Bartley as governor, one of only a few instances of this happening in the United States in high offices.

Bartley was born in Fayette County, Pennsylvania. After attending school in Virginia, he moved to Jefferson County, Ohio. Following his service under General William Henry Harrison in the War of 1812, Bartley moved to Richfield County, Ohio, near Mansfield. Engaged as a farmer, he served in the Ohio State Senate from 1816-1818. Elected to the United States House of Representatives in 1822, Bartley served four terms before declining to be renominated in 1830. He ran for governor in 1844 as a Whig - his son was a Democrat - after the candidate whom the Whigs had originally nominated, David Spangler, declined the nomination. Bartley served a single term from 1844-1846 before retiring once again.