Megazone 23 (メガゾーン23, Megazōn Tsū Surī) is a three-part Japanese mecha original video animation co-created by Noboru Ishiguro and Hiroyuki Hoshiyama, written by Hoshiyama and Emu Arii, and directed by Ishiguro, Ichiro Itano, Kenichi Yatagai, and Shinji Aramaki. The series debuted in 1985. It was originally titled Omega Zone 23 (オメガゾーン23, Omega Zōn Tsū Surī) but the title was changed just before release.

The story follows Shougo Yahagi, a delinquent motorcyclist whose possession of a government prototype bike leads him to discover the truth about the city. Released on the VHS, Betamax, Laserdisc and VHD formats, the first part was a major commercial success in Japan upon release in 1985. It was also adapted into Robotech: The Movie (1986) in North America. The film's concept of a simulated reality has drawn comparisons to later films including Dark City (1998), The Matrix (1999) and Existenz (1999). It also inspired the video game 13 Sentinels: Aegis Rim (2019).