John Mahan

John Mahan, (January 26, 1851 – 1895?) was a 19th-century Irish-born American bare-knuckle boxer and pugilist. He was a noted heavyweight fighter in the Northeastern United States during the 1870s and billed as having "an unbeaten record" until his prizefight with future heavyweight champion John L. Sullivan in 1881. Sullivan rose to national prominence as a result of his victory while Mahan went into semi-retirement, taking part in numerous exhibition bouts during the 1880s. Mahan later toured the U.S. with Sullivan and became one of his chief sparring partners.

One-time coroner of Jersey City, New Jersey, he was also involved in New York City politics with Boss Tweed during his boxing career and later involved in the Tweed Ring.