List of DC Comics characters: O
O
- O'Brian, Patrick "Eel" (also known as Plastic Man)
- O'Brien, Kyle (also known as Green Guardsman) (Amalgam Comics)
- O'Brien, Seamus (also known as Deathtrap) (WildStorm)
- O'Casey, Lance (Fawcett Comics)
- O'Connell, Travis
- O'Dare, Charity (see Charity)
- O'Donnel, Winston Churchill
- O'Donnell, Jack
- O'Grady, Sean (also known as Hot-Head)
- O'Hara, Miles, Chief (also known as Clancy O'Hara)
- O'Leary, Dutch
- O'Malley, P.J. (also known as Longarm) (Hasbro)
- O'Reilly, Molly (Vertigo)
- O'Riley, Red (also known as Rory O'Riley (or O'Reilly) (Fawcett Comics)
- O'Rourke
- O'Rourke
- O'Rourke, Li-san (Atari, Inc)
- O'Rourke-Singh, Erin Bia (also known as Dart) (Atari, Inc)
- O'Ryan, Devlin (also known as Reflex)
- O'Valeron, Vernon (also known as Vartox)
- Oa the Living Planet (Amalgam Comics)
- Oakley, Annie
- Obama, Barack (Warner Bros. Animation)
- Obatala (also known as Efraim Ngai)
- Obeah Man
- Oberon
- Oblivion
- Obrey, Lord
- Obsession (also known as Superwoman and Dana Dearden)
- Obsidian
- Ocean Master (also known as Orm Curry)
- Oceanus
- Ochun
- Occult, Richard (also known as Doctor Occult)
- Octavian (also known as Augustus)
- Odd Man (also known as Clay Stoner)
- Odds Renaldi
- Odets, Jeremiah
- Odin
- Oeone
- Officer Anderson
- Officer Bayas
- Officer Bellows (Fawcett Comics)
- Officer Clancy
- Officer Harkins
- Officer Kunkel
- Officer Merkel (also known as Stan Merkel)
- Officer Merlo
- Officer Morgan (Vertigo)
- Officer Murphy
- Officer Rowe
- Officer Russell
- Officer Sinkovec
- Officer Swirski (Vertigo)
- Officer Tiefenbacher
- Officer Varsos
- Officer Wilkes (Warner Bros. Animation (DCAU))
- Officer Xue
- Off-Ramp (also known as George Sloan)
- Offspring
- Ogden, J.R.
- Ognats, Jenni (also known as XS)
- Ognats, Jeven
- Ogre
- Ogun
- Ohiyesa Smith (also known as Pow Wow Smith)
- Ohm
- Ohmen (also known as Union) (WildStorm)
- Oho-Besh
- Okeontis
- Okonoko
- Oksana Verchenko (also known as White Queen (I))
- Olaf Bjornson (Quality Comics)
- Olaffson, Ewald
- Olafsdotter, Tora (also known as Ice)
- Olapet
- Old MacDonald (20th Century-Fox Television)
- Old Snake
- Old-Timer (also known as Appa Ali Apsa)
- Olga, Queen of the Cossacks (20th Century-Fox Television)
- Olia (Fawcett Comics)
- Oliver Queen (also known as Green Arrow)
- Oliversity
- Olivia Beezer
- Olivia Queen (also known as Black Canary (DC Elseworlds)
- Olivia Reynolds
- Olivia Tallow
- Ollie
- Ollie (Warner Bros. Animation (DCAU))
- Ollie's boss
- Olorun
- Olsen, Jenny
- Olsen, Jimmy (The Adventures of Superman (radio))
- Olsen, Sarah
- Ol-Vir of Daxam
- Olympia Atreides (WildStorm)
- Olympia
- Olympian
- Omac
- Omar Zingh (Fawcett Comics)
- Omega
- Omen (see Lilith)
- Omerta the Silencer (also known as Donald Campbell)
- Omni (also known as Cameron Begay)
- Omnibeast
- Omoto, Laira
- Ona Tomsen
- One-Punch Kid (also known as Annihilator and Karl Keller)
- Onimar Synn
- Onomatopoeia
- Ontiir
- Onyx (I)
- Onyx (II)
- Ool
- Oom the Mighty
- Ophidian
- Opral, Gnill (also known as Kid Psycho)
- Opto309v
- Ora
- Oracle (also known as Barbara Gordon)
- Oracle of Delphi
- Orana
- Orange
- Orca
- Ord Quelu (also known as Duplicate Boy and Quelu Ord)
- Orestes
- Organ Grinder (Warner Bros.)
- Organus
- Orion
- Orion Orton
- Orion, Adam (also known as Hunter)
- Orion, Lucas (Atari, Inc)
- Orithia
- Orlan
- Orloff, Serge
- Ornitho
- Orn-Zu
- Oro (Milestone Media)
- Ororo Munroe (also known as Wonder Woman and Princess Ororo of Themyscira) (Amalgam Comics)
- Orpheus (also known as Gavin King)
- Orpheus
- Orr, Elias (also known as Mister Orr)
- Ortiz (Warner Bros. Animation (DCAU))
- Orunmilla
- Osain
- Osborn, Harvey (Norman) (also known as Two-Faced Green Goblin and Green Goblin) (Amalgam Comics)
- Oscar Asherman
- Oscar the Gumshoe
- O-Sensei
- Osgood Pellinger
- Oshunmare
- Osira
- Osiris
- Osiris (20th Century-Fox Television)
- Osiris, Doctor (WildStorm)
- Osmium
- Osprey
- Oswald C. Cobblepot (also known as Penguin)
- Oswald Loomis (see Prankster)
- Oswald Wimple
- Otis (also known as Orville Gump)
- Otto Drexel
- Otto Octavius (Amalgam Comics)
- Outburst (also known as Mitch Anderson)
- Outlaw
- Outlaw Benton
- Outpost
- Output (also known as Cullen Thane)
- Output
- Outsider (also known as Alfred Pennyworth)
- Overload (Warner Bros. Animation)
- Overlord (also known as Sandor Fane)
- Overlord (also known as Underling)
- Overlord Prime
- Overmaster
- Override
- Overseer
- Overseer
- Overthrow
- Owen Hester
- Owlman (I-II)
- Owlwoman
- Ox
- Oxygen
- Oxygen (Warner Bros. Animation)
- Ozymandias (also known as Adrian Veidt)
- Ozymandias (also known as Adrian Veidt) (Warner Bros.)
- Ozzie
- Ozzie (Warner Bros. Animation (DCAU))
- Ozzie Nelson