Andy O'Brien (centre-back) 2010-12
George O'Brien (inside-forward) 1957-59
Paudie O'Connor (centre-back) 2017-19
Darren O'Dea (defender) 2011-12
Eugene O'Doherty (inside-forward) 1920-22
Chris O'Donnell (centre-back) 1989-91
Harry O'Grady (inside-forward) 1932-33
Mike O'Grady (winger) 1965-69
John O'Hare (striker) 1974-75
Eunan O'Kane (midfield) 2016-21
David O'Leary (centre-back) 1993-95
James 'Sean' O'Neill (full-back) 1967-74
Clarke Oduor (winger) 2017-19
Paul Okon (midfield) 2002-03
Salomon Olembe (midfield) 2003-04
Brett Ormerod (striker) 2004
Brendan Ormsby (centre-back) 1986-90
John Oster (midfield) 2004
Jack Overfield (winger) 1953-60
Carlton Palmer (midfield/centre-back) 1994-97
Ben Parker (left-back) 2003-12
Neil Parker (left-back) 1975-81
Keith Parkinson (centre-back) 1973-81
Derek Parlane (striker) 1980-83
Bill Parry (left-half) 1937-39
Billy Paynter (striker) 2010-12
Alan Peacock (striker) 1964-67
Bailey Peacock-Farrell (goalkeeper) 2015-19
Jason Pearce (centre-back) 2012-15
Tom Pearce (full-back) 2018-19
John Pearson (striker) 1987-91
Alfonso Pedraza (winger) 2017
Lee Peltier (defender) 2012-14
John Pemberton (defender) 1993-97
Jermaine Pennant (winger) 2003-04
Matthew Pennington (defender) 2017-18
Sonny Perkins (striker) 2022-25
Lucas Perri (goalkeeper) 2026-
Paul Peterson (left-back) 1966-71
Noel Peyton (inside-forward) 1958-63
Terry Phelan (full-back) 1983-86
Kalvin Phillips (midfield) 2014-22
Joel Piroe (forward) 2023-
Dominic Poleon (striker) 2012-14
Jimmy Potts (goalkeeper) 1926-34
Ian Poveda (winger) 2020-24
Aubrey Powell (inside-forward) 1935-48
Sam Powell (centre-forward) 1921-25
Bill Poyntz (inside-forward) 1921-23
Arthur Price (half-back) 1945-46
David Prutton (midfield) 2007-10
Danny Pugh (left-back/midfield) 2004-06 and 2011-14