Masanobu Ōkubo was a Japanese voice actor and film actor born on February 6, 1922, in Yamagata Prefecture, Japan. He passed away on March 31, 1987. His career spanned several decades, during which he contributed to numerous anime series, live-action films, and television dramas.

In the world of anime, Ōkubo is recognized for several key voice roles. He provided the voice of Ogai in the classic anime series Fist of the North Star, which aired from 1984 to 1987. He also voiced the character Hotsumatsua in the 1984 mecha anime series Giant Gorg and took on the role of Raski in Katri, Girl of the Meadows, a 1984 adaptation of the novel by Auni Nuolivaara. His film voice work includes the role of Zeus in the 1986 animated fantasy film Arion.

Outside of voice acting, Ōkubo had an extensive career in live-action film and television. He appears in several acclaimed movies, including a bit part as a samurai on a rooftop field in Akira Kurosawa's legendary 1954 film Seven Samurai. His other film credits include roles in Red Beard (1965), A Fugitive from the Past (1965), and Submersion of Japan (1973). On television, he had a guest role in episode 13 of the series Lone Wolf and Cub (Kozure Okami), playing the character Ōkubo Tadamasa, as noted in the query. He also played a henchman in the anime series Fūsen Shōjo Temple-chan (Temple the Balloonist), which featured several live-action actors in its voice cast. His many television drama credits include appearances in Taiga dramas such as Ryoma ga Yuku (1968) and Tokugawa Ieyasu (1983), as well as a role as a dialect instructor in the long-running series Oshin (1983).