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.
جاك أوبراين (بالإنجليزية: Jack O'Brien) هو لاعب كرة قاعدة أمريكي، ولد في 12 يونيو 1860 في فيلادلفيا في الولايات المتحدة، وتوفي بنفس المكان في 20 نوفمبر 1910. (ar)
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. (en)