Gamera 3: Revenge of Iris (ガメラ3 邪神〈イリス〉覚醒, Gamera Surī: Irisu Kakusei, lit. 'Gamera 3: Evil God Iris Awakens') is a 1999 Japanese kaiju film directed by Shusuke Kaneko, with special effects by Shinji Higuchi. Produced by Daiei Film and distributed by Toho, the film is the 11th entry in the Gamera film series, as well as the third film in the franchise's Heisei period, serving as a sequel to the 1996 film Gamera 2: Attack of Legion.

The film stars Ai Maeda as Ayana Hirasaka, a young girl who forms a psychic bond with a parasitic creature known as Iris that feeds upon the hatred that she feels for the giant turtle monster Gamera, who had unwittingly killed Ayana's parents and cat. The film also features Shinobu Nakayama and Ayako Fujitani reprising their roles as Mayumi Nagamine and Asagi Kusanagi, respectively. Hirofumi Fukuzawa portrays Gamera, while Akira Ohashi, who played Gamera in the previous film, portrays Iris.

Gamera 3: Revenge of Iris was screened at the 1999 Toronto International Film Festival, and received the Mainichi Film Concours award for Best Sound Recording in Japan. The film received generally positive reviews, with the film's special effects being lauded, and with many praising it as being one of the best entries in the Gamera film series.

However its popularity and tragic plot especially the portrayal of Gamera to be an unintentional threat to humanity also caused downward effects on the franchise indirectly, resulting in the cancellations and commercial failure of sequels and subsequent projects including "G4" and "G5", Gamera the Brave, and several anime projects where the projects in the 2000s were aimed to restore Gamera as a gallant and endearing character, taking 17 years for Kadokawa Corporation to produce a new installation, Gamera Rebirth in 2023.