Akagi means (赤城) "red castle," (赤木) "red tree," (赤き) "crimson" or (赤来) "red future" in the Japanese language, and may refer to:
- Akagi, Gunma, a village in Gunma Prefecture
- Akagi, Shimane (赤来町), a former town in Shimane Prefecture
- Akagi (manga), a manga by Nobuyuki Fukumoto
- Akagi (train), a train service in Japan
- One of two ships of the Imperial Japanese Navy:
- Japanese gunboat Akagi, which served in the Sino-Japanese War
- Japanese aircraft carrier Akagi, which served in World War II
- Mount Akagi, a mountain in the Kantō region of Japan
- Kei Akagi, a jazz pianist
- Dr. Ritsuko Akagi, a character from the anime TV series Neon Genesis Evangelion
- "Akagi", a song performed by Maximum the Hormone
- Takenori Akagi and Haruko Akagi, two sibling characters from the basketball manga and anime Slam Dunk
- Daidoji Akagi, a character and card personality in the L5R games and setting.