8. Martin Van Buren
President: Andrew Jackson, 1833-1837
Slave Owner: Yes
Born in Kinderhook, N.Y., Van Buren’s nickname was “Old Kinderhook.” That was shortened to “OK” in rallies for his failed 1840 reelection campaign. Somehow, that abbreviation evolved into the ubiquitous idiom. You can literally say that Van Buren was OK.