Siegmund Breitbart (22 February 1883 – 12 October 1925), also known popularly as Zishe or Sische Breitbart (Yiddish: ???? ???????????), was a Polish-born circus performer, vaudeville strongman and Jewish folklore hero.
He was known as the "Strongest Man in the World" and Eisenkönig ("Ironking") during the 1920s.