Helloween is a German power metal band founded in 1984 in Hamburg, West Germany by members of bands Iron Fist and Gentry. Its first lineup consisted of singer and guitarist Kai Hansen, bassist Markus Grosskopf, guitarist Michael Weikath, and drummer Ingo Schwichtenberg. After the release of a self-titled EP and their debut album Walls of Jericho in 1985, it expanded into a quintet with the addition of singer Michael Kiske, Hansen choosing to focus on guitar instead. Under this line-up, they released the Keeper of the Seven Keys albums, which established Helloween as a notable heavy metal band and led to the creation of the power metal subgenre. Hansen left the band soon after the release of Part II and was replaced by Roland Grapow. After leaving Helloween, Hansen formed Gamma Ray.