XIII

XIII may refer to:
 * 13 (number) or XIII in Roman numerals
 * 13th century in Roman numerals
 * XIII (comics), a Belgian comic book series by Jean Van Hamme and William Vance
 * XIII (2003 video game), a 2003 video game based on the comic book series
 * XIII (2020 video game), a remake of the 2003 video game
 * XIII: The Conspiracy, a TV miniseries based on the comic book series and game of the same title
 * XIII: The Series, a 2011 TV series based on the comic book series and miniseries
 * XIII (Rage album), 1998
 * XIII (Mushroomhead album), 2003
 * XIII (TNT album), 2018
 * Factor XIII, a clotting factor inside the coagulation cascade
 * Rugby league, still often known as just XIII in France due to the name Rugby once being forbidden for the league code