Takeo Iijima is a Japanese game creator, scenario writer, and novelist, primarily known for his work on horror and fantasy role-playing games. Born in Tokyo on July 31, 1963, he is a graduate of the Department of Cinema at the College of Art, Nihon University. While he is professionally credited under the names Takeo Iijima and Takiya Iijima, his birth name and an earlier pen name is Takeo Iijima.

Iijima began his career in the game industry at Koei (now Koei Tecmo) in 1986, working on historical simulation games. He left after one year to co-found the company Brain Gray, where he made his debut as a creator with the 1987 game Nukenin Densetsu. His first major success came with the 1988 title Last Armageddon. Following this, he departed Brain Gray and established his own company, Pandora Box, under which he became highly active as a writer and producer.

His work is heavily associated with the ONI series, a franchise of role-playing games. He served as the producer for the Super Famicom title Tōma Kishinden ONI, and later wrote the main scenario for ONI Zero: Fukkatsu on the PlayStation as part of the Pandora MAX Series. Other notable games from this period for which he wrote scenarios include the BURAI series, G Gundam: The Battle, and the horror visual novel Gakkō no Atta Kowai Hanashi (Scary Stories from School), which he also directed.

After a period of inactivity in the early 2000s, Iijima returned to the industry in 2006 under the name Takiya Iijima. His later work includes writing the scenario for the PlayStation 2 game 48 (Kari). He subsequently founded the company Shanon to manage the intellectual property from Pandora Box and began releasing independent works through his doujin circle. A notable later project is the Apathy series, which continues the world of his earlier horror game Gakkō no Atta Kowai Hanashi. He returned to console game development in 2018 and released a new entry in the Apathy series, Apathy: Narukami Gakuen Nanafushigi, in 2021.