Kinnikuman (キン肉マン, lit. transl. "Muscle Man") is a Japanese manga series created by the duo Yoshinori Nakai and Takashi Shimada, known as Yudetamago. It follows Suguru Kinniku, a superhero who must win a wrestling tournament to retain the title of prince of Planet Kinniku. Nakai and Takashi planned the series when they were attending high school originally as a parody to Ultraman.

The manga was originally published in Shueisha's shōnen manga magazine Weekly Shōnen Jump from 1979 to 1987, and was first adapted by Toei Animation into a 137-episode anime series broadcast on Nippon Television from 1983 to 1986. It restarted publication in 2011 in Shueisha's web magazine Shū Play News, and has spawned spin-off manga and anime series, video games, anime films, and several Kinnikuman-related merchandise.

There is also a sequel, the Kinnikuman: The 2nd Generation (キン肉マンII世, Kinnikuman II Sei, known as Ultimate Muscle outside Japan) manga that was serialized in Weekly Playboy between 1998 and 2004. It was published in North America by Viz Media under the title of Ultimate Muscle. It was also adapted into three different television series, all of which were broadcast on TV Tokyo in Japan and released in North America by 4Kids Entertainment.

Kinnikuman is one of the best-selling manga series in Japan, selling over 77 million copies by 2021. As popular as was the anime series and its merchandise, such as Kinkeshi, a line of action figures released as M.U.S.C.L.E. in North America. It received the Shogakukan Manga Award for children's manga in 1984.

A new anime television series adaptation produced by Production I.G, based on the 2011 revival manga and celebrating the 40th anniversary of the original anime television series, is set to premiere in 2024.