James Joseph Tunney (May 25, 1897 – November 7, 1978) was an Irish-American professional boxer who competed from 1915 to 1928. He held the world heavyweight title from 1926 to 1928, and the American light heavyweight title twice between 1922 and 1923.

A highly technical boxer, Tunney had a five-fight light heavyweight rivalry with Harry Greb in which he won three, lost once, and drew once, though many ringside reporters believed Greb should have won the decision in their second meeting. Tunney also knocked out Georges Carpentier and defeated Jack Dempsey twice; first in 1926 and again in 1927. Tunney's successful title defense against Dempsey remains one of the most famous bouts in boxing history and is known as The Long Count Fight. He retired undefeated as a heavyweight after his victory over Tom Heeney in 1928, after which Tunney was named the inaugural Fighter of the Year by The Ring magazine.