Kazuo Umezu, also known as Kazuo Umezz, was a Japanese manga artist, musician, and actor born on September 3, 1936, in Kōya, Wakayama Prefecture. He is widely recognized as one of the most important figures in the history of horror manga, often referred to as the god of horror manga. His career began in the 1950s, and he remained active until his retirement from regular manga serialization in the mid-1990s, later returning to creative work through painting. He died on October 28, 2024.

Umezu was inspired to draw manga after reading Osamu Tezuka's Shin Takarajima in elementary school, and his early work was also influenced by the Japanese folk tales his father told him. He made his professional debut in 1955 at age 18 with Mori no Kyōdai, a manga based on the fairy tale Hansel and Gretel. In his early career, he was associated with the gekiga movement, which sought to present manga as a more serious, adult-oriented art form. He also began drawing shōjo manga for magazines such as Shōjo Book. A significant breakthrough came after he moved to Tokyo in 1963, when he began developing a unique style that blended the delicate aesthetics of shōjo manga with grotesque and gruesome horror imagery, as seen in works like Reptilia. This approach broke with industry conventions and helped create a boom in horror manga during the late 1960s.

Umezu created numerous successful and influential manga series across several decades. His notable works include The Drifting Classroom, a science fiction horror series about a school transported to a post-apocalyptic future, which won the 20th Shogakukan Manga Award in 1974. He also created the comedy manga Makoto-chan, which became a major hit and introduced his signature Gwash hand gesture. Other significant titles include the horror series Cat Eyed Boy, the science fiction manga My Name Is Shingo and Fourteen, as well as Orochi and God's Left Hand, Devil's Right Hand.

The works of Kazuo Umezu have been adapted into various other media. The manga Cat Eyed Boy was adapted into a 22-episode anime television series called Yōkaiden Nekome Kozō, which aired in 1976. It was also adapted into a live-action film in 2006. Umezu is also credited as the original creator for the anime Umezu Kazuo no Noroi. Other live-action film adaptations of his work include The Snake Girl and the Silver-Haired Witch (1968) and multiple versions of The Drifting Classroom. He also made cameo appearances in some film adaptations of his own work.

Recurring themes in Umezu's work include the conflict between children and adults, with children often portrayed as more adaptable and logical than the untrustworthy or monstrous adult figures. He drew heavily from Japanese folklore, populating his stories with monsters and demons that were not purely evil, sometimes evoking compassion. He coined the term fear manga to describe his work, distinguishing it from simple grotesque tales by focusing on a psychological shudder. A central philosophical idea in his work was perspectivism, where horror and comedy are relative to the viewer's position, a concept he encapsulated by saying that being chased is horror while doing the chasing is a gag. His stories also frequently explored the terror that can exist within a family, challenging the idealized portrayals common in some earlier manga.

Kazuo Umezu's industry significance is immense. He is credited with pioneering and vitalizing the horror genre in manga, directly inspiring a new generation of artists. Among those who cite him as a major influence are Junji Ito, Toru Yamazaki, and Minetarō Mochizuki. Rumiko Takahashi briefly worked as his assistant during the creation of Makoto-chan. For his contributions, he received the Shogakukan Manga Award, the Prize for Inheritance at the Angoulême International Comics Festival, and the Commissioner for Cultural Affairs award from Japan's Agency for Cultural Affairs. He was also a notable public figure in Japan, famous for his distinctive red-and-white-striped shirt and his Gwash hand gesture.