Mutsumi Sasaki is a Japanese actor and voice actor born on July 20, 1961, in Hokkaido, Japan. He is affiliated with the theatre company Engeki Shuudan En. Sasaki stands 178 cm tall and his voice is classified as a high baritone-tenor. His personal hobbies and skills include calligraphy.

Sasaki began his career in the 1980s with stage acting before expanding into television dramas, films, and voice acting from the 1990s onward. His foundation in theatre, including full membership in Engeki Shuudan En achieved in 1986, has supported a versatile performance career spanning multiple decades.

In anime, Sasaki is recognized for a wide range of supporting roles. He is known for playing Biwamaru, a blind traveling lute priest, in the 2019 series Dororo. He also voiced the character Burroughs in the Mobile Suit Gundam Thunderbolt series and its compilation film, Mobile Suit Gundam Thunderbolt: December Sky. Other notable anime credits include Kazuo Shinohara in the animated film Summer Wars, the Chief Priest in Lu Over the Wall, Aki's Grandfather in Silver Spoon, Abuhachi in Megalo Box, Hajime Usami in My Dress-Up Darling, and roles in The Seven Deadly Sins, Barakamon, and The Witch and the Beast. He has also contributed to video games, lending his voice to characters such as Charles Dickens in Assassin's Creed Syndicate and Eleazar Fig in Hogwarts Legacy.

Beyond animation, Sasaki is highly active in dubbing foreign films and television series. He is the regular Japanese dubbing voice for actor Toby Jones, taking on his roles in numerous productions including the Marvel Cinematic Universe, the Pirates of the Caribbean films, and the series My Dress-Up Darling. His dubbing work spans major Hollywood films and western animated properties. Additionally, Sasaki appears frequently in Japanese live-action television, particularly in NHK's taiga historical dramas, as well as in other popular series and stage productions of classical works.