Movie War Mega Max featured the first seven Kamen Riders (Kamen Rider 1, 2, V3, Riderman, X, Amazon, and Stronger) to commemorate the franchise's 40th anniversary. Trailers for the film shown during airings of Fourze also showed the return of Kamen Rider Double as well as a new form for Kamen Rider OOO. Unlike previous Movie War films, where they were divided into 3 segments, Movie War Mega Max is divided into 5 parts. Like previous Movie War films the secondary Kamen Rider of Kamen Rider Fourze, Kamen Rider Meteor, made his debut in the film.
as Gentaro Kisaragi / Kamen Rider Fourze
as Eiji Hino / Kamen Rider OOO
as Shotaro Hidari / Kamen Rider W / Kamen Rider Joker
as Philip / Kamen Rider W
as Ankh
as Nadeshiko Misaki / Kamen Rider Nadeshiko
as Kamen Rider 1 (voice)
as Kamen Rider 2 (voice)
as Kamen Rider V3 (voice)
as Riderman (voice)
as Kamen Rider X (voice)
as Kamen Rider Amazon (voice)
as Kamen Rider Stronger (voice)
as Hina Izumi
as Chiyoko Shiraishi
as Erika Satonaka
as Akira Date / Kamen Rider Proto-Birth
as Shintaro Goto / Kamen Rider Birth
as Birth Driver (voice) / Birth Buster (voice)
as O Scanner (voice) / Poseidon Driver (voice) / GingaOh Driver (voice)
as Kamen Rider Poseidon (voice)
as Miharu Minato / Kamen Rider Aqua
as Kōsei Kōgami
as Gaia Memory (voice)
as Katal
as Solaris
as Chancellor Kiima
as Lem Kannagi
as Kengo Utahoshi
as Yūki Jōjima
as Shun Daimonji
as Miu Kazashiro
as Tomoko Nozama
as JK
as Chūta Ōsugi
as Mitsuaki Gamō
as Virgo Zodiarts (voice)
as Mysterious student
