James Leo O'Neill
- Bats Right, Throws Right
- Height 5' 10½", Weight 165 lb.
- Debut April 15, 1920
- Final Game July 29, 1923
- Born February 23, 1893 in Minooka, PA USA
- Died September 5, 1976 in Chambersburg, PA USA
Jim O'Neill is the brother of Jack O'Neill, Mike O'Neill, and Steve O'Neill. Jim is listed as the regular shortstop for the 1920 Washington Senators. He was five years younger than teammate Walter Johnson. He came back to the Senators in 1923 for 23 games.
Jim wasn't in pro ball in 1921-22. The SABR biography of Steve O'Neill says that Jim's career was shortened because of injuries, so perhaps he was injured in 1921-22. An article  refers to a benefit being held for Jimmy as he was stricken with pneumonia and hadn't been able to play since then.
Jim had played for the Buffalo Bisons in 1916-17 and the Shreveport Gassers in 1918-19 before coming to the majors. He played again in the minors during part of 1923 and during 1924-28. For three years from 1924-26, he was with the Omaha Buffaloes.