Kōzō Shioya was a Japanese actor and voice actor from Kagoshima Prefecture, born on August 18, 1955. He was active in the industry for nearly six decades, from 1966 until his death on January 20, 2026, at the age of 70 from a cerebral hemorrhage. Throughout his extensive career, he was represented by the talent agency Aoni Production. He was the older brother of fellow voice actor Yoku Shioya.

Shioya's career was marked by a vast number of roles across anime, video games, and dubbing for foreign films and television series. He was a regular presence in Japanese animation, often lending his voice to secondary characters, villains, and creatures. He had a long association with the long-running Dragon Ball franchise, where his most iconic role was that of the childlike but immensely powerful Majin Boo in Dragon Ball Z and subsequent series, films, and video games. His other notable anime roles include Chūtora in Ginga Nagareboshi Gin, Isamu Amami and Polonaise in The King of Braves GaoGaiGar, and multiple characters in the GeGeGe no Kitarō series, most prominently Konaki-Jijii. He also had significant roles in One Piece as Genzo, Pappag, and Edward Weevil, and in Slam Dunk as Kazushi Hasegawa and Nozomi Takamiya. His filmography also included roles such as Motokichi Kinuta in World Trigger, Chūsei Tatsuno in Dinosaur King, Yukihiro Kiyomizu in The Millionaire Detective - Balance: UNLIMITED, Toy Majin in the Fresh Precure! movie, and Bullhorn in Transformers: Super God Masterforce.

Beyond animation, Shioya was a prolific voice actor in video games. He voiced the bomber Fatman in Metal Gear Solid 2: Sons of Liberty and provided the Japanese voice of Nikita Khrushchev in Metal Gear Solid 3: Snake Eater. He also voiced the character Imagawa Yoshimoto in the Sengoku Basara game series. His work extended to tokusatsu live-action series, with guest appearances in shows like Bakuryū Sentai Abaranger and Zyuden Sentai Kyoryuger. He was also a familiar voice in Japanese dubs of foreign media, providing voices for characters such as Porthos in The Three Musketeers, Duck in Thomas & Friends, and the White Rabbit in Tim Burton's Alice in Wonderland.