MLB Players — O
411 MLB baseball players with last names starting with O.
- O'Berry, Mike 1979–1985
- O'Brien, Billy 1884–1890
- O'Brien, Bob 1971–1971
- O'Brien, Buck 1911–1913
- O'Brien, Charlie 1985–2000
- O'Brien, Cinders 1888–1891
- O'Brien, Dan 1978–1979
- O'Brien, Darby 1887–1892
- O'Brien, Dink 1923–1923
- O'Brien, Eddie 1953–1958
- O'Brien, George 1915–1915
- O'Brien, Jack 1882–1890
- O'Brien, John 1884–1884
- O'Brien, Johnny 1953–1959
- O'Brien, Pete 1887–1890
- O'Brien, Peter 2015–2019
- O'Brien, Ray 1916–1916
- O'Brien, Riley 2021–
- O'Brien, Syd 1969–1972
- O'Brien, Tom 1882–1890
- O'Brien, Tommy 1943–1950
- O'Bryant, Willie
- O'Connell, Danny 1950–1962
- O'Connell, Jimmy 1923–1924
- O'Connell, John 1891–1902
- O'Connell, Pat 1886–1886
- O'Connor, Andy 1908–1908
- O'Connor, Brian 2000–2000
- O'Connor, Dan 1890–1890
- O'Connor, Frank 1893–1893
- O'Connor, Jack 1887–1910
- O'Connor, Johnny 1916–1916
- O'Connor, Mike 2006–2011
- O'Connor, Paddy 1908–1918
- O'Day, Darren 2008–2022
- O'Day, Hank 1884–1890
- O'Dea, Ken 1935–1946
- O'Dea, Paul 1944–1945
- O'Dell, Billy 1954–1967
- O'Donnell, George 1954–1954
- O'Donnell, Harry 1927–1927
- O'Donnell, John 1884–1884
- O'Donoghue, John 1963–1971
- O'Doul, Lefty 1919–1934
- O'Farrell, Bob 1915–1935
- O'Flaherty, Eric 2006–2017
- O'Grady, Brian 2019–2021
- O'Grady, Chris 2017–2018
- O'Hagan, Hal 1892–1902
- O'Halloran, Greg 1994–1994
- O'Hara, Bill 1909–1910
- O'Hara, Kid 1904–1904
- O'Hara, Tom 1906–1907
- O'Hearn, Ryan 2018–
- O'Hoppe, Logan 2022–
- O'Keefe,
- O'Keefe, Brian 2022–
- O'Leary, Charley 1904–1934
- O'Leary, Dan 1879–1884
- O'Leary, Troy 1993–2003
- O'Loughlin, Jack 2024–
- O'Loughlin, Patrick 1883–1883
- O'Loughlin, Silk
- O'Malley, Ryan 2006–2006
- O'Malley, Shawn 2014–2016
- O'Malley, Tom 1982–1990
- O'Malley, Walter
- O'Mara, Ollie 1912–1919
- O'Meara, Eddie 1895–1896
- O'Neal, Luther
- O'Neal, Oran 1925–1927
- O'Neal, Randy 1984–1990
- O'Neil, Buck
- O'Neil, Charles
- O'Neil, Ed 1890–1890
- O'Neil, Fancy 1874–1874
- O'Neil, John 1899–1902
- O'Neil, Mickey 1919–1927
- O'Neill, Dennis 1893–1893
- O'Neill, Emmett 1943–1946
- O'Neill, Fred 1887–1887
- O'Neill, Harry 1922–1923
- O'Neill, Hugh 1875–1875
- O'Neill, Jack 1902–1906
- O'Neill, Jim 1920–1923
- O'Neill, John 1904–1906
- O'Neill, Mike 1901–1907
- O'Neill, Paul 1985–2001
- O'Neill, Peaches 1904–1904
- O'Neill, Steve 1911–1928
- O'Neill, Tip 1883–1892
- O'Neill, Tyler 2018–
- O'Riley, Don 1969–1970
- O'Rourke, 1872–1872
- O'Rourke, Frank 1912–1931
- O'Rourke, Jim 1959–1959
- O'Rourke, Jimmy 1908–1908
- O'Rourke, Joe 1929–1929
- O'Rourke, John 1879–1883
- O'Rourke, Mike 1890–1890
- O'Rourke, Patsy 1908–1908
- O'Rourke, Ryan 2015–2019
- O'Rourke, Tim 1890–1894
- O'Rourke, Tom 1887–1890
- O'Sullivan, Sean 2009–2016
- O'Toole, Denny 1969–1973
- O'Toole, Jim 1958–1967
- O'Toole, Marty 1908–1914
- Oakes, Rebel 1909–1915
- Oakley, Charles
- Oaks, Trevor 2018–2018
- Oana, Prince 1934–1945
- Oates, Johnny 1970–1981
- Obando, Sherman 1993–1997
- Ober, Bailey 2021–
- Oberbeck, Henry 1883–1884
- Oberg, Scott 2015–2019
- Oberholtzer, Brett 2013–2016
- Oberkfell, Ken 1977–1992
- Oberlander, Doc 1888–1888
- Oberlin, Frank 1906–1910
- Obermueller, Wes 2002–2007
- Obradovich, Jim 1978–1978
- Ochoa, Alex 1995–2002
- Ochoa, Ivan 2008–2008
- Ock, Whitey 1935–1935
- Ockey, Walter 1944–1944
- Oden, Johnnie
- Odenwald, Ted 1921–1922
- Odom, Blue Moon 1964–1976
- Odom, Dave 1943–1943
- Odom, Heinie 1925–1925
- Odom, Joseph 2020–2021
- Odom, Sam
- Odor, Rougned 2014–
- Odorizzi, Jake 2012–2022
- Odwell, Fred 1904–1907
- Oelkers, Bryan 1983–1986
- Oeltjen, Trent 2009–2011
- Oertel, Chuck 1958–1958
- Oeschger, Joe 1914–1925
- Oester, Ron 1978–1990
- Offerman, Jose 1990–2005
- Office, Rowland 1972–1983
- Offutt, Mose
- Ogando, Alexi 2010–2018
- Ogando, Cristofer 2022–2022
- Ogando, Nefi 2015–2016
- Ogasawara, Shinnosuke 2025–
- Ogden, Curly 1922–1926
- Ogden, Jack 1918–1932
- Ogea, Chad 1994–1999
- Oglesby, Jim 1936–1936
- Oglivie, Ben 1971–1986
- Ogrodowski, Bruce 1936–1937
- Ogrodowski, Joe 1925–1925
- Oh, Seunghwan 2016–2019
- Ohka, Tomo 1999–2009
- Ohl, Joe 1909–1909
- Ohl, Pierson 2025–
- Ohlendorf, Ross 2007–2016
- Ohlman, Mike 2017–2017
- Ohman, Will 2000–2012
- Ohme, Kevin 2003–2003
- Ohtani, Shohei 2018–
- Ojala, Kirt 1997–1999
- Ojeda, Augie 2000–2010
- Ojeda, Bob 1980–1994
- Ojeda, Miguel 2003–2006
- Okajima, Hideki 2007–2013
- Okert, Steven 2016–
- Okey, Chris 2022–
- Okrie, Frank 1920–1920
- Okrie, Len 1948–1952
- Olander, Jim 1991–1991
- Olave, Pedro
- Oldfield, Dave 1883–1886
- Oldham, Jimmy
- Oldham, John 1956–1956
- Oldham, Red 1914–1926
- Oldis, Bob 1953–1963
- Oldring, Rube 1905–1918
- Olerud, John 1989–2005
- Olin, Frank 1884–1885
- Olin, Steve 1989–1992
- Oliva, Jared 2020–2021
- Oliva, Jose 1994–1995
- Oliva, Tony 1962–1976
- Olivares, Ed 1960–1961
- Olivares, Edward 2020–
- Olivares, Omar 1990–2001
- Oliver, Al 1968–1985
- Oliver, Andy 2010–2011
- Oliver, Bob 1965–1975
- Oliver, Darren 1993–2013
- Oliver, Dave 1977–1977
- Oliver, Gene 1959–1969
- Oliver, Jim
- Oliver, Joe 1989–2001
- Oliver, John Henry
- Oliver, Nate 1963–1969
- Oliver, Tom 1930–1933
- Olivera, Hector 2015–2016
- Oliveras, Francisco 1989–1992
- Oliveros, Lester 2011–2014
- Olivo, Chi-Chi 1961–1966
- Olivo, Diomedes 1960–1963
- Olivo, Miguel 2002–2014
- Oller, Adam 2022–
- Ollom, Jim 1966–1967
- Olmedo, Ray 2003–2012
- Olmo, Luis 1943–1951
- Olmos, Edgar 2013–2015
- Olmstead, Fred 1908–1911
- Olmsted, Al 1980–1980
- Olmsted, Hank 1905–1905
- Olsen, Barney 1941–1941
- Olsen, Kevin 2001–2003
- Olsen, Ole 1922–1923
- Olsen, Scott 2005–2010
- Olsen, Vern 1939–1946
- Olson, Garrett 2007–2012
- Olson, Greg 1989–1993
- Olson, Gregg 1988–2001
- Olson, Ivy 1911–1924
- Olson, Karl 1951–1957
- Olson, Marv 1931–1933
- Olson, Matt 2016–
- Olson, Reese 2023–
- Olson, Ted 1936–1938
- Olson, Tim 2004–2005
- Olson, Tyler 2015–2019
- Olt, Mike 2012–2015
- Olwine, Ed 1986–1988
- Omeada,
- Omogrosso, Brian 2012–2013
- Oms, Alejandro 1925–1935
- Ona, Jorge 2020–2020
- Ondrusek, Logan 2010–2016
- Onis, Manuel 1935–1935
- Onslow, Eddie 1912–1927
- Onslow, Jack 1912–1917
- Ontiveros, Steve 1973–1980
- Oquendo, Jose 1983–1995
- Oquist, Mike 1993–1999
- Oran, Tom 1875–1875
- Orange,
- Orange, Grady
- Oravetz, Ernie 1955–1956
- Ordaz, Luis 1997–2006
- Ordenana, Tony 1943–1943
- Ordonez, Magglio 1997–2011
- Ordonez, Rey 1996–2004
- Orengo, Joe 1939–1945
- Orf, Nate 2018–2020
- Orie, Kevin 1997–2002
- Orlando, Paulo 2015–2018
- Orme, Clarence
- Orme, George 1920–1920
- Orndorff, Jess 1907–1907
- Ornelas, Jonathan 2023–
- Ornelas, Tirso 2025–
- Oropesa, Eddie 2001–2004
- Orosco, Jesse 1979–2003
- Orr, Billy 1913–1914
- Orr, Dave 1883–1890
- Orr, Pete 2005–2013
- Orrell, Joe 1943–1945
- Orsatti, Ernie 1927–1935
- Orsino, John 1961–1967
- Orsulak, Joe 1983–1997
- Ort, Kaleb 2021–
- Orta, Jorge 1972–1987
- Ortega, Anthony 2009–2009
- Ortega, Bill 2001–2001
- Ortega, Jose 2012–2014
- Ortega, Oliver 2021–
- Ortega, Phil 1960–1969
- Ortega, Rafael 2012–
- Ortenzio, Frank 1973–1973
- Orth, Al 1895–1909
- Ortiz, Danny 2017–2017
- Ortiz, David 1997–2016
- Ortiz, Hector 1998–2002
- Ortiz, Javier 1990–1991
- Ortiz, Joe 2013–2013
- Ortiz, Joey 2023–
- Ortiz, Jose 1969–1971
- Ortiz, Junior 1982–1994
- Ortiz, Luis 1993–1996
- Ortiz, Oliverio 1944–1944
- Ortiz, Rafaelito
- Ortiz, Ramon 1999–2013
- Ortiz, Roberto 1941–1950
- Ortiz, Russ 1998–2010
- Ortmeier, Daniel 2005–2008
- Orton, John 1989–1993
- Orvella, Chad 2005–2007
- Orwoll, Ossie 1928–1929
- Orze, Eric 2024–
- Osborn, Bob 1925–1931
- Osborn, Fred 1907–1909
- Osborn, Ozzie 1975–1975
- Osborne, Bobo 1957–1963
- Osborne, Donovan 1992–2004
- Osborne, Fred 1890–1890
- Osborne, Tiny 1922–1925
- Osborne, Wayne 1935–1936
- Osburn, Pat 1974–1975
- Osgood, Charlie 1944–1944
- Osich, Josh 2015–2021
- Osik, Keith 1996–2005
- Osinski, Dan 1962–1970
- Osley, Julius
- Osoria, Franquelis 2005–2008
- Ostdiek, Harry 1904–1908
- Osteen, Champ 1903–1909
- Osteen, Claude 1957–1975
- Osteen, Darrell 1965–1970
- Ostendorf, Fred 1914–1914
- Oster, Bill 1954–1954
- Ostergard, Red 1921–1921
- Osterhout, Charlie 1879–1879
- Ostermueller, Fritz 1934–1948
- Osting, Jimmy 2001–2002
- Ostrosser, Brian 1973–1973
- Ostrowski, Joe 1948–1952
- Ostrowski, Johnny 1943–1950
- Osuna, Al 1990–1996
- Osuna, Alejandro 2025–
- Osuna, Antonio 1995–2005
- Osuna, Jose 2017–2020
- Osuna, Roberto 2015–2020
- Oswalt, Corey 2018–2021
- Oswalt, Roy 2001–2013
- Otanez, Willis 1998–1999
- Otañez, Michel 2024–
- Otero, Dan 2012–2019
- Otero, Reggie 1945–1945
- Otero, Ricky 1995–1997
- Otey, Bill 1907–1911
- Otis, Amos 1967–1984
- Otis, Bill 1912–1912
- Otis, Harry 1909–1909
- Otsuka, Akinori 2004–2007
- Ott, Billy 1962–1964
- Ott, Ed 1974–1981
- Ott, Mel 1926–1947
- Ottavino, Adam 2010–
- Otten, Jim 1974–1981
- Otten, John 1895–1895
- Otterson, Billy 1887–1887
- Otto, Dave 1987–1994
- Otto, Glenn 2021–2023
- Ouellette, Phil 1986–1986
- Oulliber, Johnny 1933–1933
- Ousley, Guy
- Outen, Bill 1933–1933
- Outlaw, Jimmy 1937–1949
- Outman, James 2022–
- Outman, Josh 2008–2014
- Overall, Orval 1905–1913
- Overbay, Lyle 2001–2014
- Overmire, Stubby 1943–1952
- Overton, Albert
- Overton, Connor 2021–
- Overton, Dillon 2016–2017
- Overy, Mike 1976–1976
- Oviedo, Johan 2020–
- Oviedo, Juan Carlos 2005–2014
- Oviedo, Luis 2021–2021
- Ovitz, Ernie 1911–1911
- Owchinko, Bob 1976–1986
- Owen, Dave 1983–1988
- Owen, Frank 1901–1909
- Owen, Hunter 2021–2021
- Owen, Larry 1981–1988
- Owen, Marv 1931–1940
- Owen, Mickey 1937–1954
- Owen, Spike 1983–1995
- Owens, Albert
- Owens, Aubrey
- Owens, Dewitt
- Owens, Eric 1995–2003
- Owens, Henry 2006–2007
- Owens, Jack 1935–1935
- Owens, Jayhawk 1993–1996
- Owens, Jerry 2006–2009
- Owens, Jim 1955–1967
- Owens, Judge
- Owens, Oscar
- Owens, Paul
- Owens, Red 1899–1905
- Owens, Roosevelt
- Owens, Rudy 2014–2014
- Owens, Smoky
- Owens, Sylvester
- Owens, Tyler 2025–
- Owens, Will
- Owens, Yip 1905–1915
- Owings, Chris 2013–
- Owings, Micah 2007–2012
- Ownbey, Rick 1982–1986
- Oxley, Henry 1884–1884
- Oxspring, Chris 2005–2005
- Oyler, Andy 1902–1902
- Oyler, Ray 1965–1970
- Ozark, Danny
- Ozmer, Horace 1923–1923
- Ozuna, Marcell 2013–
- Ozuna, Pablo 2000–2008