| Bob O'Brien | |
| Position: | Pitcher |
| Birth Date: | 23 April 1949 |
| Birth Place: | Pittsburgh, Pennsylvania, U.S. |
| Bats: | Left |
| Throws: | Left |
| Debutleague: | MLB |
| Debutdate: | April 11 |
| Debutyear: | 1971 |
| Debutteam: | Los Angeles Dodgers |
| Finalleague: | MLB |
| Finaldate: | July 7 |
| Finalyear: | 1971 |
| Finalteam: | Los Angeles Dodgers |
| Statleague: | MLB |
| Stat1label: | Win–loss record |
| Stat1value: | 2–2 |
| Stat2label: | Earned run average |
| Stat2value: | 3.00 |
| Stat3label: | Strikeouts |
| Stat3value: | 15 |
| Teams: | |
Robert Allen O'Brien (born April 23, 1949) is an American former pitcher in Major League Baseball. He pitched in 14 games for the Los Angeles Dodgers during the 1971 season, including four starts and one shutout.
O'Brien was acquired along with Doyle Alexander, Sergio Robles and Royle Stillman by the Baltimore Orioles from the Dodgers for Frank Robinson and Pete Richert at the Winter Meetings on December 2, 1971.[1]