Jack Sharkey, born October 6, 1902 in Binghamton, New York, United States – died August 17, 1994 in Beverly, Massachusetts, was a heavyweight boxing champion.

Born in an era when prizefighters, actors and others in the public spotlight adopted an "American-sounding" pseudonym, Josef Paul Zukauskas took the family name of a popular retired Irish boxer and future Hall of Famer, "Sailor Tom" Sharkey (1873-1953).

In 1929, in a fight held in Yankee Stadium, Jack Sharkey knocked out the former light-heavyweight champion, Tommy Loughran to win the United States heavyweight title. His victory earned him the opportunity to fight for the vacant world title against the German contender, Max Schmeling. In their June 12, 1930, championship fight, Sharkey was disqualified in the fourth round after delivering a punch that landed below Schmeling's belt. This is the only occasion in boxing history when the heavyweight championship was won by disqualification.

In October of 1931, Sharkey defeated the highly regarded Italian heavyweight, Primo Carnera, and was then given another chance to fight for the title. On June 21, 1932 at the Madison Square Garden Bowl in Long Island City, New York, Jack Sharkey defeated Max Schmeling in their rematch to win the World Heavyweight Boxing Championship in a very controversal split descision.

Sharkey lost his championship on June 29, 1933 in his second fight with Primo Carnera.

In 1994, Jack Sharkey was inducted into the International Boxing Hall of Fame.