Odie: [USA] The lovable, drooling and dumb-as-a-door dog from Jim Davis' series Garfield & Friends.
Ofelia: [Spain] The secretary at T.I.A. from Francisco Ibáñez' series Mortadelo y Filemón.
Ogee [USA] The girl who want to buy Magilla Gorilla (Hanna & Barbera).
Old Man: [USA] Former hero from Jim Krueger's series Foot Soldiers.
Old Trusty: [USA] Retired police dog from Disney.
Olga Lawina: [Netherlands] Freelance agent from Martin Lodewijk's series Agent 327.
Olive Oyl: [USA] Popeye's sweetheart from Elzie Crisler Segar's series Popeye the Sailor.
Oliver Owl: [USA] Henery Hawk's friend, the goody two-shoes owl (Looney Tunes).
Oliver Queen:
Olle: [USA] Swedish name for Moe, the bully from Bill Watterson's series Calvin and Hobbes.
Omni-Man: [USA] Character from Robert Kirkman's part of the Image Universe.
Ondine: [USA] Character from Avalon Studios.
Onkel Joakim: [USA] Danish name for Uncle Scrooge, the World's richest duck (Disney).
Opelichanec: [USA] Czech name for Emil Eagle, the evil genius from Disney.
Oracle: [USA] Barbara Gordon from DC Comics (post-crisis New Earth/Earth-0).
Orel Emil: [USA] Czech name for Emil Eagle, the evil genius from Disney.
Orel Karel: [USA] Czech name for Emil Eagle, the evil genius from Disney.
Orson:
Oscar Rapace: [USA] French name for Emil Eagle, the evil genius from Disney.
Osvald: [USA] Danish name for Irwin Troll, the happy troll from Russell Myers' series Broom-Hilda.
Oswald the Lucky Rabbit: [USA] Walt Disney's original rascal.
Oto Orel: [USA] Czech name for Emil Eagle, the evil genius from Disney.
Otto:
Otto Orel: [USA] Czech name for Emil Eagle, the evil genius from Disney.
Ottoperotto: [Italy] The Beagle Boys' dog (Disney).
Owl: [United Kingdom] The wise bird from A. A. Milne and Disney's series Winnie the Pooh.
Ozymandias: [USA] Character from Alan Moore's Watchmen (DC Comics).