Fumio Watanabe was a Japanese actor and voice actor born on October 31, 1929, in Tokyo. He passed away on August 4, 2004, at the age of 74. A graduate of the University of Tokyo, he began his career in the entertainment industry after joining the Shochiku film studio in 1956.

Watanabe is primarily renowned for his extensive work in live-action film, particularly his frequent collaborations with acclaimed director Nagisa Oshima, a key figure in the Japanese New Wave. His filmography includes numerous notable movies from the 1950s through the 1970s, such as Black River, Cruel Story of Youth, Death by Hanging, Boy, The Ceremony, and the first two films in the Female Convict Scorpion series.

While his career was predominantly in live-action cinema, Watanabe also contributed voice work to animation. His most frequently cited voice acting role is in the 1967 film Band of Ninja, where he provided the voices for the characters Oda Nobunaga and Kennyo. He is also credited with voice work in the anime Ultra Seven, providing the voice for the character Hatsumoto, known as "Gen" in some adaptations, as well as for the 1995 animated film adaptation of the manga Sanctuary.

His body of work reflects recurring professional relationships with many prominent figures in Japanese cinema. Beyond his frequent work with director Nagisa Oshima, his filmography shows he often appeared alongside actors such as Kei Satō, Tetsurō Tanba, Hōsei Komatsu, and Bunta Sugawara.