Total Count: 94 players registered.

Pos  Name                  From  To
  C  O'Brien, Charlie      1999-1999
RHP  O'Connell, Ronan      2050-2060
LHP  O'Connor, Johnny      2025-2036
 RF  O'Dea, Simon          2043-2055
RHP  O'Donnell, Ian        2041-2055
 3B  O'Donoghue, Joe       2036-2040
 RF  O'Grady, Steve        2030-2041
 RF  O'Leary, Troy         1999-2012
 LF  O'Neal, Darius        2007-2022
 RF  O'Neill, Paul         1999-2005

Pos  Name                  From  To
LHP  Obertan, Fausto       2052-2060
 CF  Obinna, Christian     2050-2060
 RF  Ochoa, Alex           1999-2012
RHP  Ochoa, Rodrigo        2043-2060
RHP  Od, Al                1999-2008
 3B  Odabasi, Mehmet       2035-2045
RHP  Offerman, Drummond    2029-2043
 SS  Offerman, Jose        1999-2009
RHP  Ogasawara, Koji       2048-2060
 2B  Ogden, Bill           2020-2032

Pos  Name                  From  To
RHP  Ogea, Chad            1997-2009
RHP  Ogura, Keiji          2033-2049
 3B  Oh, Sadahura          1997-2014
RHP  Oh, Trent             2060-2060
RHP  Ohl, Sibby            2005-2019
 CF  Ojala, Jussi          2045-2057
 1B  Okonkwo, Chidi        2037-2048
RHP  Oldham, Isaac         2051-2060
 LF  Oldis, Robert         2026-2034
 1B  Olerud, John          1999-2008

Pos  Name                  From  To
RHP  Olien, Paul           2017-2030
 RF  Olin, Wid             2020-2031
 3B  Oliva, Bernardo       1999-2001
 3B  Oliva, Jose           2000-2014
 SS  Oliva, Woody          2020-2032
RHP  Olivares, Omar        1999-2006
 2B  Oliveira, Carlos      2042-2048
 1B  Oliveira, Danilo      2053-2060
 LF  Oliveira, Nelson      2040-2054
LHP  Oliver, Darren        1999-2010

Pos  Name                  From  To
 CF  Oliver, Harry         2011-2027
  C  Oliver, Joe           1999-2005
 1B  Oliver, Mickey        2040-2041
RHP  Oliver, Russ          2037-2051
LHP  Ollom, Hank           2030-2046
 RF  Olmedo, Amaury        2057-2060
 CF  Olsen, Joe            2014-2028
 LF  Olsen, Ken            2020-2031
RHP  Olson, Pat            2060-2060
 LF  Olwine, Jim           2055-2060

Pos  Name                  From  To
 1B  Omara, Mrisho         2056-2060
RHP  Omarov, Igor          2043-2059
RHP  Ondo, Denis           2055-2060
RHP  Ono, Mihara           2009-2011
 SS  Onoda, Shunsuke       2048-2060
LHP  Opalev, Aleksandr     2035-2049
  C  Oquendo, Frank        2012-2018
 2B  Oquendo, Juan         1999-2000
  C  Oquendo, Reuben       2017-2022
RHP  Ordonez, Marcelo      2051-2060

Pos  Name                  From  To
 SS  Ordonez, Rey          1997-2009
LHP  Orellano, Rafael      1999-2016
RHP  Orleans, Vendome      1997-1999
 LF  Orosco, Andy          2054-2060
LHP  Orosco, Jesse         1999-2001
 CF  Orozco, Nicolas       2043-2057
 SS  Orozco, Oribe         2049-2058
RHP  Ortega, Alejandro     2054-2059
  C  Ortega, Ruben         2042-2058
 LF  Orth, Jake            2039-2040

Pos  Name                  From  To
RHP  Ortiz, Mike           2022-2030
RHP  Osborn, Carl          2036-2038
LHP  Osborne, Donovan      1999-2012
LHP  Osborno, Donovan      1997-2009
RHP  Ossus, Richie         1999-2008
LHP  Ostrosser, Ed         2059-2060
RHP  Ostrowski, Albert     2018-2021
RHP  Osuna, Antonio        1999-2014
 3B  Oswalt, Joe           2027-2045
 3B  Otanez, Willis        1999-2013

Pos  Name                  From  To
 SS  Otero, Ramiro         2036-2051
 LF  Otero, Ricky          1999-2011
 LF  Otey, Mother          2032-2051
 3B  Otoyo, Noto           1997-1997
 RF  Ott, Mel              1997-2014
 2B  Otto, Drew            2033-2046
RHP  Otto, Frank           2045-2058
LHP  Outlaw, Ron           2027-2036
RHP  Overstreet, Mike      2025-2038
 1B  Oviedo, Ramon         2043-2058

Pos  Name                  From  To
 2B  Owen, Buck            2018-2020
 LF  Owens, Eric           1999-2013
  C  Owens, Jayhawk        1999-2007
 CF  Owusu, Hart           2039-2042