- Onigiri
- Oniichan dakedo Ai sae Areba Kankeinai yo ne!
- Oniichan dakedo Ai sae Areba Kankeinai yo ne! Specials
- Oniichan wa Oshimai!
- Oniichan wa Oshimai! (Uncensored)
- Onikirimaru
- Onimomomomo
- Onimusha
- Onipan!
- Onmyou Kaiten Re:Birth
- Onmyouji
- Onyankopon
- Ookami-san to Shichinin no Nakama-tachi
- Oomuro-ke
- Oomuro-ke: Dear Friends
- Oooku
- Ooyasan wa Shishunki!
- Opus.COLORs
- Orange
- Orange: Mirai
- Ore ga Ojousama Gakkou ni "Shomin Sample" Toshite Gets♥Sareta Ken Specials
- Ore ga Suki nano wa Imouto dakedo Imouto ja Nai Specials
- Ore no Kanojo to Osananajimi ga Shuraba Sugiru
- Ore no Nounai Sentakushi ga, Gakuen Love Comedy wo Zenryoku de Jama Shiteiru OVA
- Ore no Sora Keiji-hen
- Ore wo Suki nano wa Omae dake ka yo
- Ore wo Suki nano wa Omae dake ka yo: Oretachi no Game Set
- Oreca Battle
- Orenchi no Furo Jijou
- ORESUKI Are you the only one who loves me: Game Over
- Orient
- Orient: Awajishima Gekitou-hen
- Osake wa Fuufu ni Natte kara: Yuzu Atsukan
- Osananajimi ga Zettai ni Makenai Love Comedy
- Oshiete Mahou no Pendulum: Rilu Rilu Fairilu
- Osomatsu-kun (1988)
- Osomatsu-san 3rd Season
- Otaku no Seiza
- Otaku no Video
- Otogizoushi
- Otome Game no Hametsu Flag shika Nai Akuyaku Reijou ni Tensei shiteshimatta... OVA
- Otome Youkai Zakuro Picture Drama
- Otona no Bouguya-san II
- Ouran Koukou Host Club
- Outbreak Company
- Outlanders
- Oval x Over
- Over Drive
- Overflow
- Overflow (Uncensored)
- Overlord
- Overlord II
- Overlord III
- Overlord IV
- Overlord Movie 1: Fushisha no Ou
- Overlord Movie 2: Shikkoku no Eiyuu
- Overlord Movie 3: Sei Oukoku-hen
- Overlord: Ple Ple Pleiades
- Overlord: Ple Ple Pleiades - Clementine Toubou-hen
- Overlord: Ple Ple Pleiades 2
- Overlord: Ple Ple Pleiades 3
- Overlord: Ple Ple Pleiades 4
- Overman King Gainer
- Overtake!
- Owari no Seraph: Kyuuketsuki Shahar
- Owarimonogatari
- Owarimonogatari 2nd Season
- Ozanari Dungeon: Kaze no Tou
- Ozma
- Ozmafia!!
- Seihou Bukyou Outlaw Star
- Seikimatsu Occult Gakuin
- Seikimatsu Occult Gakuin Specials
- Shenguo Zhi Shang
- Tsuru ni Notte: Tomoko no Bouken
- Tudi Ge Ge Shi Da Lao
- Urasekai Picnic
- Wagaya no Oinari-sama.
- Wakaokami wa Shougakusei!
- Wakaokami wa Shougakusei! Movie
- Wanpaku Ouji no Orochi Taiji
- Windaria
- Yi Ren Jun Moye
- Zhen Dao Ge
- Zhen Dao Ge 2nd Season
- Zhen Dao Ge 3rd Season
