John K. O'Brien (born John K. Byrne, June 12, 1860 – November 20, 1910) was an American Major League Baseball player. He played primarily catcher and first base from 1882 to 1890 in the American Association.
External links
- Career statistics from Baseball Reference, or Baseball Reference (Minors)
- Baseball Almanac
- Jack O'Brien at SABR (Baseball BioProject)
