The original line-up featured Kai Hansen (Vocals/Guitars), Michael Weikath (Guitars), Markus Grosskopf (Bass) and Ingo Schwichtenberg (Drums). In 1984 the band had signed a deal with Noise Records (see 1984 in music) and recorded two songs for a Noise compilation record called Death Metal with bands Hellhammer, Running Wild and Dark Avenger. The two tracks were "Oernst Of Life" by Weikath, and Hansen's "Metal Invaders" which later on was featured in a faster version on the band's first full-length album.
1985 came around and Helloween recorded its first record Helloween, a self-titled EP containing 5 tracks. The EP was successful. During that same year the group recorded and released its first full-length album titled Walls of Jericho which was well-received, with its mixture of speed and melodies redefining heavy metal. (In Fact, WWE Wrestler Chris Jericho took his stage name from the album, as well as the name of his signature submission move, Walls Of Jericho). However, during the following tour, it became obvious that Kai had difficulties singing and playing the guitar at the same time. Kai's last recorded performance as the band's lead singer was in 1986 on a single EP titled Judas, which contained the song "Judas" along with some live tracks. After that, Helloween began the search for a new vocalist.