Isao Sasaki is a Japanese actor, voice actor, and singer.
He has had voice roles in anime such as Legend of the Galactic Heroes, Space Battleship Yamato, and Gatchaman. He has also performed the opening themes for anime such as Yamato, Star of the Giants, Getter Robo, Casshern, Grendizer, Gaiking and tokusatsu series such as Himitsu Sentai Gorenger, J.A.K.Q. Dengekitai, Choujinki Metalder, and most recently Tokusou Sentai Dekaranger. He has also had an acting role in the tokusatsu film Kamen Rider ZO, OOO, Den-O, All Riders: Let's Go Kamen Riders and in the series Kyojuu Tokusou Juspion. He is also known for dubbing over Sylvester Stallone, and Christopher Reeve.
As an actor, Sasaki was Selected for the lead role in Nagisa Ōshima's film The Sun's Burial in 1960 by Ōshima. Sasaki played the leading roles in seven films when he was an actor under contract with Shochiku studio. In 1969, he landed lead role on the TV jidaigeki Yōjutsu Bugeichō.