Richard M. Johnson

He was thought to have been the soldier who killed Tecumseh in battle.

Source

Richard Mentor Johnson

Richard M. Johnson, a Kentucky politician, was Martin Van Buren's Vice President.  One of the most unique aspects of his life, however, was his common-law marriage to Julia Chinn, who was 1/8 black.  He and Julia had two daughters.  After Julia's death, he had two other common-law marriages with slave women.