Kamen Rider OOO is a 2010-2011 Japanese tokusatsu drama in Toei Company's Kamen Rider Series, being the twelfth series in the Heisei period run and the twenty-first overall. It began airing on September 5, 2010, the week following the conclusion of Kamen Rider W, joining Tensou Sentai Goseiger and then Kaizoku Sentai Gokaiger in the Super Hero Time lineup, until its conclusion on August 28, 2011. The series' titular Kamen Rider made a cameo appearance in the film Kamen Rider W Forever: A to Z/The Gaia Memories of Fate. Due to the events of episodes 27 and 28 it is suggested that the series is a meta entry in the franchise that goes beyond the continuity of previous series and movies including its own films.
The catchphrase for the series is "I'll transform!!!".