GaoGaiGar (勇者王ガオガイガー, Yūsha Ō GaoGaiGā?) is a Japanese anime television series series begun in 1997, created by Sunrise's internal "Studio 7" under the direction of Yoshitomo Yonetani, and was the eighth and final Yuusha or "Brave" metaseries funded by Takara and produced by Sunrise. It takes place in 2005 (initially referred to as only "the 21st Century"), two years following an incident where the first identified extraterrestrial intelligence—classified as "EI-01"—crash-landed on Earth and absorbed a large number of machines into itself before disappearing without a trace. Following this incident, the Japanese government created a secret organization to combat potential alien threats: the Gutsy Geoid Guard, or "GGG," based beneath G-Island City in Tokyo Bay. Parasitic alien lifeforms known as "Zonderians" have begun to emerge; using the Zonder Metal of which they are made, they can assimilate various kinds of matter to form "Zonders." which use humanoid beings as their hosts.

The Gutsy Geoid Guard gains three key resources with which to combat this threat: Galeon, a sentient mechanical lion of alien design; the alien child Mamoru Amami, whom Galeon had left with human parents eight years earlier; and the human cyborg Guy Shishioh, whose life was saved by Galeon two years earlier and is capable of fusing with him, forming the mechanoid GaiGar. When combined with the GGG-made GaoMachines, GaiGar becomes the Super Mechanoid GaoGaiGar: a mecha capable of defeating Zonders, recovering their cores for Mamoru to "purify" and saving the human host in doing so.

On April 19, 2006, Media Blasters announced their licensing of the GaoGaiGar TV series for marketing in the United States. The first volume was released to stores on September 26, 2006. On April 23rd 2007, it was reported that the US release of GaoGaiGar would go on hiatus due to the company's focus on a labor-intensive Voltron DVD release. They followed with a statement that the subsequent volumes will be subtitled only, due to badly-timed and scheduled releases of the DVDs resulting in poor sales.