Lucifer (リュシフェル, Ryushiferu) (stylized as Λucifer) was a Japanese rock band, best known for contributing several of their songs to the popular anime, Kaikan Phrase. The band was formed in 1999, and disbanded in early 2003. They officially debuted on 15 September 1999 with their big hit single Datenshi BLUE, and became increasingly popular thereafter.

Lucifer was put together for the Kaikan Phrase anime to promote it. The anime was based on the a popular shōjo manga by Mayu Shinjo. The band members of real life Lucifer changed their names to match with their anime/manga counterparts, except for the vocalist, who kept his name instead of changing it to Sakuya (the main character's name). Several of Lucifer's songs were used in the anime, along with songs from other bands like Glay, Feel and e.MU. However, the band decided to go on even after the anime had ended, and continued to release more music afterwards.