* Obake no Holly
* Obake no Q-Taro (1965)
* Obake no Q-Taro (1971)
* Obake no Q-Taro (1985)
* Ōban Star Racers
* Obocchama-kun
* Ocha-ken ~Chokotto no Gatari~ (2003)
* Ocha-ken ~Ri Kotto no Gatari~ (2006)
* Occhi di Gatto (early episodes)
* Occhi di Gatto (later episodes)
* Occhio ai fantasmi!
* Un oceano di avventure
* Ochamegami Monogatari Kolokolo Polon
* Ochame-na Futago -Clare Gakuin Monogatari-
* O Czym Szumia Wierzby
* Odenkun The Adventures of Odenkun
* Odysseus 31
* Offside
* Ogon Bat
* Ogon Senshi Gold Lightan
* Ogon Yuusha Goldran
* Ohayo! Spank
* Oh Dorobo Jing
* Oh Edo Rocket
* Oh! Family
* Oh! My Kosobu
* Oh! My Goddess (1998)
* Oh! My Goddess (2005)
* Oh! My Goddess (2006)
* Oh! Super Milk-chan
* Oideyo! Henamon Sekai Kasumin (2001)
* Oideyo! Henamon Sekai Kasumin (2002)
* Oi! Ryoma
* L'Oiseau Bleu
* Oishinbo
* Oja-Majo Doremi (1999)
* Oja-Majo Doremi # (2000)
* Oja-Majo Doremi Dokkaan (2002)
* Ojamajo Doremi Na-i-sho (2004)
* Ojamanga Yamada-kun
* Ojarumaru (1998)
* Ojarumaru (1999)
* Ojarumaru (2000)
* Ojarumaru (2001)
* Ojarumaru (2002)
* Ojarumaru (2003)
* Ojarumaru (2004)
* Ojarumaru (2005)
* Ojarumaru (2006)
* Ojarumaru (2007)
* Ojarumaru (2008)
* Okami Shonen Ken
* Okami to Koushinryo
* Okawari Boy Starzan-S
* Okusama wa Joshikôsei
* Okusama wa Mahou Shoujo
* Olga's no Russia Gokuza
* Olive et Tom
* Omakase Scrappers
* Omishi Mahou Gekijou Risky Safety
* Onbu Obake
* Onegai My Melody (2005)
* Onegai My Melody Kirara (2008)
* Onegai My Melody ~Kuru Kuru Shuffle!~ (2006)
* Onegai My Melody Sukkiri (2007)
* Onegai Samia Don
* Onegai Teacher
* Onegai Twins
* One Piece
* Oniisama E ...
* Only You Viva! Kabakura
* Onmyou Taisenki
* Ookiku Funikabutte
* Opowiesci z Palmowego Miasteczka
* Oraa Guzura Dado (1967)
* Oraa Guzura Dado (1987)
* Ordy et les Grandes Découvertes
* Ore wa Chokkaku
* Ore wa Teppei
* Orguss
* Oroshitate Musical Nerima Daikon Brothers
* Oruchuban Ebichu
* Osomatsu-kun (1966)
* Osomatsu-kun (1988)
* Otogi Jushi Akazukin
* Otogi Manga Calendar
* Otogi Story Tenshi no Shippo
* Otogi Zoushi
* Otoko do Aho! Koshien
* Otoko Ippiki Gakidaisho
* Otome wa Boku ni Koishiteru
* Ouran Koukou Host Club
* Ouran High School Host Club
* Outlaw Star
* Over Drive
* OVERMAN King Gainer
* Ox Tales
* Oyayubi Hime Monogatari
* Oyoneko Bunyan
* Oz no Mahoutsukai
* Oz no Uchu Daiboken