Osamu Kobayashi was a Japanese actor and voice actor born on November 22, 1934, in Tokyo. He began his career in theatre as a research student before joining the Literary Seat theater company. Following the company's disbandment, he was affiliated with the Tokyo Actors' Cooperative Association and eventually founded his own voice actor management company, Dojinsha Production, where he served as the representative director and executive director. Kobayashi was a baritone, a vocal quality that made him well-suited for authoritative and mature roles, often portraying high-ranking officials and fatherly figures. His career in voice acting spanned from the early days of overseas dubbing to animation, and he remained active until his death on June 28, 2011, from pancreatic cancer at the age of 76.

Kobayashi's voice became widely recognized through his many roles in classic anime, particularly within the science fiction genre. One of his most iconic and recurring roles was in the Space Battleship Yamato series, where he first played General Domel in the original 1974 series and continued to appear in nearly every subsequent installment, including as Emperor Zwordar in Space Battleship Yamato II, Captain Jiro Dan in Space Battleship Yamato III, and Osamu Yamanami in the film Be Forever Yamato. His other notable anime roles from this era included the title character in the 1967 series Ogon Bat, Azbes and Mardal in Panzer World Galient, Sabarath and Savalas in GoShogun, Boone in the film Phoenix 2772, and John Thornton in Call of the Wild: Howl, Buck. He also took on significant roles in later years, such as the Emperor of China in the Japanese dubs of Disney's Mulan and Mulan II, and the prospector Stinky Pete in Toy Story 2.

In addition to his work in Japanese animation, Kobayashi had a prolific career in dubbing foreign films and television series. He was particularly famous for being the dedicated Japanese voice of actor Yul Brynner, dubbing his performances in numerous films such as The Magnificent Seven, Anastasia, Taras Bulba, and Westworld. He also provided the Japanese voice for many other prominent actors, including John Wayne, Jon Voight, Michael Caine, and Gene Hackman across various films. His extensive dubbing credits also included the role of Alastor "Mad-Eye" Moody in the Japanese-language versions of the Harry Potter films, Ulysses in the NHK edition of Space Legend Ulysses 31, and Emperor Exhaus in the tokusatsu series Gekisou Sentai Carranger.

Throughout his long and distinguished career, Kobayashi's contributions to the voice acting industry were significant. In recognition of his lasting impact and body of work, he was posthumously awarded the Special Achievement Award at the 6th Seiyu Awards in 2012.