51

51 may refer to:
 * 51 (number)
 * The year
 * 51 BC
 * AD 51
 * 1951
 * 2051
 * 51 (film), a 2011 American horror film directed by Jason Connery
 * "Fifty-One", an episode of the American television drama series Breaking Bad
 * 51 (album), a 2012 mixtape by rapper Kool A.D.
 * "Fifty One", a song by Karma to Burn from the album V, 2011
 * 51 Nemausa, a main-belt asteroid