Demon Detective Loki: RAGNAROK) is a manga by Sakura Kinoshita published from August 1999 to October 2004.

A television anime based on the manga series ran for 26 episodes from April 5, 2003, to September 27, 2003, in Japan.

The series originally ran in the magazine Monthly Shōnen Gangan under the name The Mythical Detective Loki (魔探偵ロキ, Matantei Loki), but Ragnarok was added to the title when the series was purchased by publishing company MAG Garden and moved to Comic Blade magazine.

The Mythical Detective Loki Ragnarok ran for 5 more volumes, which were published in Japan by Blade Comics, and picked up for translation and English release by ADV Manga.

Japanese Limited Editions These were often packaged with special extras, such as audio drama CDs or collectible figurines.