Gamera Rebirth (stylized as GAMERA -Rebirth-) is a Japanese original net animation (ONA) series directed and co-written by Hiroyuki Seshita [ja]. Produced by Kadokawa Corporation and animated by ENGI, it is a reboot of the Gamera franchise following Gamera the Brave (2006), the first animated entry in the franchise and the first entry in the franchise's Reiwa era. The series was released worldwide on Netflix on September 7, 2023, and a re-edited edition consisting of 12 episodes was broadcast on NHK General TV from April to June in 2025.

During summer 1989, three elementary students witness Gamera in battle as monsters converge on Tokyo before they annihilate most of humanity.

On November 16, 2022, Kadokawa announced plans for a new Gamera production, entitled Gamera Rebirth, which will be released globally on Netflix. Shusuke Kaneko, director of the Heisei Gamera trilogy, had proposed an idea for a new film. However, Kadokawa had already proceeded with their new project by the time Kaneko presented his pitch. Regardless, Kaneko had expressed his support for the project. A figure of Gamera was exhibited at Tamashii Nation 2022 between November 18 and 20, along with a newspaper featuring Gamera that was distributed at the event.

In February 2023, Kadokawa revealed the cast and staff. The series would be animated by ENGI, with Hiroyuki Seshita directing, who co-directed Polygon Pictures' Godzilla anime trilogy, Tetsu Iijima producing, Atsushi Tamura designing the characters, and Kan Takahama designing the monsters. A teaser released in January debuted footage, albeit briefly, from the series and revealed that it would consist of six episodes and feature five additional enemy monsters. In March, Kadokawa released a new key visual poster, a synopsis, and a full trailer. ENGI was originally launched to focus on 2D anime, and 3D CGI department was newly established for Gamera Rebirth. As the company was relatively new and most of its creators are young, production of Gamera Rebirth and building ENGI's CGI department were simultaneously progressed, drastically increasing the difficulty of the production.

The series is designated as a tribute to Noriaki Yuasa and to stay faithful to previous productions especially the Showa films, where the time setting of the series (1989) is to represent both eras of Showa and Heisei, and a number of references to previous films and scrapped projects and unused ideas were made. Designs of Gamera and Gyaos, and the first scene of Gamera to fight against a flock of small Gyaos in the first episode were reused from the 2015 short film, and Katsuhito Ishii, the director of the 2015 short film was credited as the designer of Gamera. Gamera's design was modified from the 2015 version to portray him being less intimidating, and to emphasize his intelligence, gentleness, and dignity.

Seshita approved the offer for the Netflix series partially because Kadokawa approved his request to focus on kaiju battles which he couldn't achieve in the Godzilla anime trilogy. He originally prepared fighting scenes twice or five times more than actual ones, including more diverse abilities and characteristics of kaiju, however he had to cut them due to budget and schedule, and noted the difficulty to insert kaiju battles in every episode due to budgetary constraints. One of policies for battle scenes was to prevent human casualties by Gamera, therefore such depictions were avoided during Gamera's appearances in early episodes in Tokyo; Gamera arrived at Tokyo after most evacuations were completed, and he threw Gyaos and Jiger at open areas without people. This direction was also effective to reduce production costs. Seshita also highlighted the concept of "children, who have been protected by Gamera, in return protect Gamera".

The titles of each episodes are references to classic films and other productions; Kanał, Run Silent, Run Deep, Daiei Film's Destiny's Son The Moon Is a Harsh Mistress, Childhood's End, and Aura Battler Dunbine. Aura Battler Dunbine was directly mentioned and an actual publication of Dunbine was briefly depicted within the first episode; its episode title and the location (Nishi-Shinjuku) were tributes to Yoshiyuki Tomino by Shinichiro Inoue [ja] as Inoue was once an editor in charge of Tomino including the Dunbine publication, and Inoue specially gained a permission to use the book from Arata Sasaki [ja] for the reference.

Japanese punk rock band Wanima provided both opening and ending songs, Natsuake and FLY&DIVE (jp). An acoustic version of Gamera March [ja], the iconic song used in Showa films and other medias, was also inserted.