William Smith O'Brien
- Bats Right, Throws Unknown
- Height 6' 0", Weight 185 lb.
- Debut September 27, 1884
- Final Game August 12, 1890
- Born March 14, 1860 in Albany, NY USA
- Died May 26, 1911 in Kansas City, MO USA
Billy O'Brien played five seasons in the majors, appearing in three different major leagues. He started in the 1884 Union Association as a third baseman, pitcher and first baseman, and then spent three years in the National League (1887-1889) with the Washington Nationals, mostly playing first base. In his last major league season, he was with the 1890 Brooklyn Gladiators of the American Association, playing exclusively first base.
He led the 1887 National League in home runs and was also among league leaders in home runs in 1888 and 1890.
Billy also had a long minor league career, playing multiple seasons for teams such as St. Paul, Kansas City, Nashville, Denver and Sioux City. With Nashville in 1886 he had an ERA of 1.27 in 14 games pitched.
The book The Baseball Rookies Encyclopedia has a photo of O'Brien, and says that his 19 home runs in 1887 set a rookie record at the time.
The book Baseball in Minnesota says O'Brien was a star for Minneapolis before he moved to St. Paul as a young player.
- NL Home Runs Leader (1887)