Directors: O
- Billy O'Brien2
- Fergus O'Brien1
- Jesse O'Brien1
- Jim O'Brien1
- Steve O'Brien1
- Kate O'Callaghan1
- Matt O'Casey2
- Jim O'Connolly8
- Andrew O'Connor1
- Daniel O'Connor1
- Danny O'Connor1
- Frances O'Connor1
- Geoffrey O'Connor2
- Pat O'Connor7
- Tom O'Dell1
- Damien O'Donnell3
- George More O'Ferrall7
- Colm O'Gorman1
- Jim O'Hanlon3
- Gerry O'Hara15
- Tommy O'Haver1
- Michael O'Herlihy1
- Ronan O'Leary1
- Brian O’Malley1
- Bryan O'Neil1
- Jevon O'Neill1
- Ken O'Neill2
- Ronan O'Rahilly1
- George O'Reilly1
- Steve O'Rourke1
- Phil O'Shea1
- Sinéad O'Shea1
- Shane O'Sullivan2
- Thaddeus O'Sullivan4
- Claire Oakley1
- Georgia Oakley2
- James Oakley1
- C.J. Obasi1
- Elizabeth F Obisanya1
- Mike Ockrent1
- Hilmar Oddsson1
- Sias Odendaal1
- Jonas Odenheimer1
- Jekaterina Oertel1
- Paula van der Oest1
- Colin Offland1
- Hikaru Okita1
- Kristín Ólafsdóttir1
- Tony Oldham2
- Gary Oldman1
- William Oldroyd2
- Annette K. Olesen1
- Laurence Olivier3
- Dan Ollerhead1
- Ermanno Olmi2
- Adura Onashile1
- Daina Oniunas-Pusic1
- Yoko Ono3
- Rishi Opel1
- Marcel Ophuls1
- Joshua Oppenheimer3
- Steve Oram1
- Paul Oremland2
- Stuart Orme3
- James Ormerod1
- Nick Ormerod1
- Alex Orwell1
- Nagisa Ōshima1
- Louise Osmond5
- Ruben Östlund1
- Olatunde Osunsanmi1
- Simon Otto1
- Jackie Oudney1
- Idrissa Ouédraogo2
- Damien Ounouri1
- Gérard Oury1
- Horace Ové2
- Cliff Owen11
- Jonny Owen2
- Martin Owen3
- Jan Oxenberg1
- Chris Oxley1
- Berkun Oya1
- Femi Oyeniran2
- Frank Oz3
- François Ozon2
- Ferzan Özpetek1