Hiroya Oku is a Japanese manga artist born in Fukuoka, Japan, on September 16, 1967. He is the original creator behind several major manga and anime properties, including the science fiction series Gantz and Inuyashiki. Early in his career, Oku used the pseudonym Kuon Yahiro. He was a runner-up in the 1988 Young Jump Youth Manga Awards for his debut work, Hen, which was his first serialized manga.

Oku began his career as a professional manga artist with Hen, a romantic comedy that was originally published in two parts. His next work, Zero One, was a series about a video game tournament that was ultimately cancelled due to poor reception. However, Oku achieved international recognition with his next project, Gantz, which was serialized in the magazine Weekly Young Jump from 2000 to 2013. This series, collected in 37 volumes, became his most renowned work and established his signature style of blending science fiction with explicit violence and psychological drama. Following the conclusion of Gantz, he created Inuyashiki, a story about an elderly man transformed into a powerful machine, which ran from 2014 to 2017.

As a creator, Oku is known for his pioneering use of digital processing for manga backgrounds. His narratives often feature ordinary people placed in extraordinary and violent circumstances, exploring themes of life, death, and morality. His works commonly contain explicit violence, gore, and sexual situations, as well as matters considered taboo by the public. Oku has cited manga artists Katsuhiro Otomo and Ryoichi Ikegami as major influences on his work.

Several of Oku's manga have been adapted into other media. The first major adaptation was the Gantz anime series, produced by the studio Gonzo. This was followed by a two-part live-action film series: Gantz (2011) and Gantz II: Perfect Answer (2011), both directed by Shinsuke Sato. The franchise was later adapted into a full 3D CG anime film, GANTZ:O, released in 2016. His next major work, Inuyashiki, was adapted into an anime television series titled Inuyashiki Last Hero, produced by the studio MAPPA, which aired in 2017. Beyond his manga and anime work, Oku also contributed to the video game industry by designing a character named Shura for Namco Bandai's fighting game Soulcalibur IV.