Hiroo Sasaki is a Japanese voice actor, or seiyuu, born on September 9th in Akita Prefecture, Japan. He is affiliated with the talent agency 81 Produce.

Sasaki's path to becoming a voice actor was fueled by a childhood passion for anime and video games, particularly Mobile Suit Gundam and the Super Robot Wars game series, where seeing the same voice actors portray different characters sparked his interest in the profession. During high school, he honed his performance skills as a member of the broadcasting club, creating radio dramas and participating in reading competitions. After graduating, he moved to Tokyo and enrolled in the Yoyogi Animation Academy. His entry into the industry was marked by perseverance; he auditioned for 81 Produce multiple times before finally being accepted, which allowed him to make his professional debut in 2008.

Sasaki has built a versatile career with a wide range of roles in anime, video games, and foreign film dubbing. In anime, he is known for several key parts. He voiced Vidaux Völker in the time-traveling series RErideD and Hank Johnson in Ingress: The Animation. He played Lee, a crew member on a dragon-hunting airship, in Drifting Dragons. In the popular sports franchise Kuroko's Basketball, he voiced Hiroshi Fukuda, a role he also reprised in the film Gekijōban Kuroko no Basuke Last Game. He is also recognized for his work in the Smile PreCure! series, where he voiced the characters Akanbee, Hyper Akanbee, and Super Akanbee; the series was localized for an international audience as Glitter Force.

Beyond these roles, Sasaki's extensive filmography includes performances in acclaimed series such as JoJo's Bizarre Adventure, Fate/Zero, Golden Kamuy, and the Japanese dub of the Chinese animation Fox Spirit Matchmaker. His work also extends significantly into video games and voice dubbing for overseas films and television series, including titles like Call of Duty: Modern Warfare II & III and the Japanese versions of Hollywood films such as Green Book and Jungle Cruise.

Sasaki is noted for his dedication and reliability in the competitive voice acting industry. He is fluent in the Akita dialect and lists singing, basketball, and boxing among his hobbies and special skills. His early career experience included preparing tea and snacks in the recording studio, a common task for junior members, even while he was beginning to land significant character roles.