Keikou Sakai is a Japanese voice actor born on December 25, 1972, in Fukushima Prefecture. He is affiliated with the talent agency 81 Produce. He is a graduate of the Amusement Media Academy.

Sakai began his voice acting career in the early 2000s, initially voicing background and supporting characters in various anime series. His portfolio expanded to include a wide range of roles in anime, video games, and film dubbing. He is also known for his work in tokusatsu series such as Kamen Rider and Super Sentai, where he often provides voices for monsters and other special characters.

Sakai has voiced characters in several long-running and popular anime franchises. His notable roles include Raijin and Waraji in Naruto, Agonosuke in Gintama, Kingman in MegaMan NT Warrior, and Tank Lepanto in One Piece. He also voiced Bug-Eaten in JoJo's Bizarre Adventure and a bear in Laid-Back Camp. In the Pokémon anime, he provided the voice for Gozu.

A recurring and prominent role in his career is Sweden (Berwald Oxenstierna) in the long-running Hetalia franchise. He has voiced this character in multiple installments, including Hetalia: Axis Powers, Hetalia: The World Twinkle, and Hetalia: World Stars. His work on this series also extends to drama CDs and character CDs.

His voice acting work also extends to video games. Recent notable game roles include Hoolay in Honkai: Star Rail and Grad in Grand Summoners. Earlier game credits include Protectos the Goreroid in Mega Man ZX and Serizawa Kamo in Bakumatsu Renka Shinsengumi.

In addition to his work in Japanese animation and games, Sakai is active in dubbing Western films and television series into Japanese. His dubbing credits include providing voices for characters in productions such as Prison Break, Stargate Atlantis, and the film Cars 2.