Isao Sasaki, born on May 16, 1942, in Tokyo, is a highly influential Japanese actor, voice actor, and singer whose career has spanned over six decades. He is a graduate of the private Musashi Junior and Senior High School. Sasaki began his entertainment career in 1960 as a rockabilly singer, a career start that earned him the nickname "the Japanese Elvis Presley". He made his film acting debut the same year, appearing in Nagisa Oshima's The Sun's Burial.

His entry into voice acting came in 1972 when he was cast as Joe Asakura, also known as Joe the Condor, in the seminal anime series Science Ninja Team Gatchaman. This role marked the beginning of a prolific voice acting career. The following year, he began singing theme songs for anime, starting with Casshan, which led to him becoming one of the most recognized voices in anime music.

Sasaki's deep, resonant voice made him a natural fit for heroic and authoritative characters. He is particularly renowned for his extensive work in the Space Battleship Yamato franchise. He voiced Hajime Saito in Farewell to Space Battleship Yamato (1978) and the subsequent Space Battleship Yamato II television series. He later took on the role of Daisuke Shima in Final Yamato (1983). His connection to the series extends beyond voice acting, as he also performed its iconic theme song.

He continued to reprise and take on new roles within the Gatchaman universe, playing Joe the Condor in Gatchaman II (1978), Gatchaman Fighter (1979), and the 1978 Gatchaman The Movie. His filmography includes a wide array of other notable anime roles. He voiced Duke Freed in Uchu Enban Daisenso (1975), the villain Mendosa in The Mysterious Cities of Gold (1982), and Erich Von Haltenberg in Legend of the Galactic Heroes (1998). He also played Soji Ozuma in Dai Yamato Zero-go and, more recently, took on the role of Danblf in the 2022 series She Professed Herself Pupil of the Wise Man, as well as the character Zhao Yun in Sangokushi II: Amakakeru Otokotachi.

In addition to his anime work, Sasaki is a giant in the world of anime and tokusatsu music. He has performed the opening themes for legendary series such as Getter Robo, Casshan, UFO Robot Grendizer, and Gaiking, as well as tokusatsu hits like Himitsu Sentai Gorenger and J.A.K.Q. Dengekitai. His rendition of the Space Battleship Yamato theme became a million-selling record.

Beyond animation, Sasaki has a distinguished career in live-action television and film, including a role as Professor Kenichiro Nambara in Kyojuu Tokusou Juspion and as Dr. Mochizuki in Kamen Rider ZO. He is also the longstanding Japanese dubbing voice for actors Sylvester Stallone and Christopher Reeve, becoming synonymous with characters like Rocky Balboa, John Rambo, and Superman for Japanese audiences.

Sasaki has been married to fellow voice actress Miyuki Ueda since 1981. His immense contributions to the industry have been recognized with a Special Achievement Award at the 5th Seiyu Awards in 2011 and the Anime Merit Award at the Tokyo Anime Award in 2015.