Kamen Rider: The First (仮面ライダー THE FIRST, Kamen Raidā Za Fāsuto, Masked Rider: The First) is a 2005 Japanese tokusatsu superhero film. The film is a reboot adaptation of the television series Kamen Rider, though there are many differences between the film and the original programme; some of these, however, are due to a closer reliance on the original Kamen Rider manga by Shotaro Ishinomori . Written by Toshiki Inoue and directed by Takao Nagaishi, the film stars Masaya Kikawada as Takeshi Hongo/Kamen Rider 1 and Hassei Takano as Hayato Ichimonji/Kamen Rider 2.

The film was released theatrically on November 5, 2005, though it had several early screenings around Tokyo during the previous two months, beginning on October 23, at the Tokyo Film Festival. While it was the first Kamen Rider to be released independently, it was not screened on major Toei-affiliated cinemas, and was only shown on around 20 theatres during its first day. It was released on Region 2 DVD on April 21, 2006. American anime distributor Media Blasters released the film subtitled-only on Region 1 DVD on April 3, 2007, but this version of the film is no longer in print. They did tease the possible release of the movie in 2022.

The film's theme song is "Bright! our Future" by Da Pump, though the opening features a small portion of the original Kamen Rider theme song, "Let's Go!! Rider Kick", sung by Masato Shimon.

The film was produced by Ishinomori Productions and Toei, who have also produced every previous television series and films in the Kamen Rider franchise. It was followed by a sequel, Kamen Rider: The Next.