Peter J. O'Brien (June 17, 1877 – January 31, 1917) was a Major League Baseball second baseman who played for three seasons. He played for the Cincinnati Reds in 1901, the St. Louis Browns in 1906, and the Cleveland Naps and Washington Senators in 1907.
Pete O'Brien
| Given name: | Peter J. O'Brien |
| Nicknames: | None |
| Primary Pos: | Secondbase |
| Hght/Wght: | 5'7" / 170 lbs |
| Bats/Throws: | L / R |
| Born: | Jun 17, 1877 in Binghamton, NY |
| Died: | Jan 31, 1917 in Jersey City, NJ (39 years old) |
| Debut: | Sep 21, 1901 |