Hitoshi Iwaaki is a Japanese manga artist born on July 28, 1960, in Tokyo. His interest in creating manga was sparked during high school by reading the works of Osamu Tezuka, which led him to begin drawing himself. He started his professional career as an assistant to manga artist Kazuo Kamimura in 1984. Iwaaki made his debut as a creator the following year when his short story "Gomi no Umi" (Sea of Garbage) won a newcomer award and was published in a special edition of Morning magazine.

Iwaaki is best known for creating the science-fiction and horror series Parasyte (Kiseijū), which was serialized from 1989 to 1994. The manga, which tells the story of a young man whose right hand is taken over by a parasitic alien, became a critical and commercial success, winning the Kodansha Manga Award in 1993. Following the completion of Parasyte, Iwaaki has worked on a number of other series. These include the science fiction work The Country of Tanabata (Tanabata no Kuni), the short story collection Sound of Bones (Hone no Oto), and the one-volume works Snow Ridge/Sword Dance (Yuki no Tōge, Tsurugi no Mai) and Heureka.

Since 2003, his primary work has been the ongoing historical manga Historie, which is serialized in Kodansha's Monthly Afternoon magazine. The series, which follows the life of Eumenes, a secretary and general to Alexander the Great, has been met with significant acclaim. Historie won the Grand Prize in the Manga Division at the Japan Media Arts Festival in 2010 and received the Grand Prize at the Tezuka Osamu Cultural Prize in 2012. More recently, the series won the Best General Manga award at the 49th Kodansha Manga Awards in 2025. The manga has been on hiatus since 2022 but has over 4.7 million copies in circulation. In addition to his own series, Iwaaki has contributed to tribute projects. He was credited as the original creator for the two anthology volumes Neo Parasyte m and Neo Parasyte f, which were published in 2015 and 2016 respectively, and feature short stories by various manga artists based on his Parasyte universe. He also provided the original concept for the manga Reiri, which was illustrated by Daisuke Muroi and serialized from 2015 to 2018.

The adaptation history of Iwaaki's work is substantial. Parasyte was adapted into a 24-episode anime television series titled Parasyte -the maxim- produced by Madhouse, which aired from 2014 to 2015. Concurrently, the manga was also adapted into two live-action films released in 2014 and 2015. Over a decade later, it was announced in early 2026 that Historie would receive a television anime adaptation produced by LIDENFILMS. Iwaaki noted in the announcement that he first conceived the story over forty years prior.

Iwaaki's artistic identity is characterized by a simple, powerful, and clean art style, which stands in contrast to the more ornate trends that emerged in the 1990s. His work is known for its original concepts and measured storytelling, with critics often highlighting the quality of the narrative in his acclaimed series Parasyte. His significance within the manga industry is underscored by his numerous awards and the long-running serialization of Historie, a historical epic he began after achieving success with Parasyte. His influence is such that other notable creators have contributed to tribute anthologies celebrating his most famous work.