Jack O'Neill, Irish-American baseball player (d. 1935)
John Joseph "Jack" O'Neill (10 January 1873 – 29 June 1935) was catcher in Major League Baseball who played for the St. Louis Cardinals (1902–03), Chicago Cubs (1904–05) and Boston Beaneaters (1906). He batted and threw right-handed.

He was born in the townland of Tawnaleen, near Maum, in County Galway, Ireland, to Michael O'Neill, a small farmer in Maum, and Mary Joyce.O'Neill was one of four major league brothers. Steve was a catcher and manager, Jim a shortstop, and Mike, who also was born in Ireland, was a pitcher and formed a brother battery with Jack for the St. Louis Cardinals.

O'Neill shared catching duties for the Cardinals, Cubs and Beaneaters in a modest span of five years. He was a smart runner with some speed and usually was used in pinch-running situations. His most productive season came in 1903, when he posted career-highs in batting average (.236), runs (23), hits (58), doubles (nine), runs batted in (21), stolen bases (11) and games played (75).

In 303 games O'Neill was a .196 hitter with 20 stolen bases and 74 RBI. He also collected 185 hits with 24 doubles, five triples, and one home run in 945 at-bats.

O'Neill died in Scranton, Pennsylvania, at the age of 62.