Helloween is a German power/speed metal band founded in the early 1980s by members of Iron Fist and Powerfool. Helloween are known as major innovators of power metal.

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 and recorded two songs for a Noise compilation record called Death Metal. The two tracks were "Oernst Of Life" by Weikath, and Hansen's "Metal Invaders" which later on ended up in a faster version on the bands first full-length album.

1985 came around and Helloween then recorded their first record Helloween, a self-titled EP containing 5 tracks. The EP was successful, and during that same year they recorded and released their first full-length album titled Walls of Jericho which became a critical smash, with its innovative mixture of speed and melodies. (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 performance as the band's lead-singer came in 1986 in form of 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...

The first choice was to recruit former Tyran Pace vocalist Ralf Scheepers, however the band ended up finding an 18-year-old talent from the local Hamburg band Ill Prophecy, named Michael Kiske. With their new lead singer they recorded Keeper of the Seven Keys, Part 1, released in 1987, which established Helloween as one of the most successful metal bands in Europe. In 1988 Helloween recorded Keeper of the Seven Keys Part II, their best-known album featuring the classic line-up. The band achieved even more success around the world than with "Keeper 1" and things were going extremely well.

Guitarist Kai Hansen surprisingly left the band soon after the European tour for the "Keeper 2" album due to conflicts within the band as well as troubles with the record company, and a growing dissatisfaction with life on tour. He was shortly after replaced by former Rampage guitarist Roland Grapow, who finished the rest of the "Keeper 2" tour with the band.

In 1989 the band released a live album called Live In The UK, featuring live material from their 1988 European tour, entitled Keepers Live in Japan and I Want Out Live in US. The remaining members continued on, but label problems kept them from touring and releasing new material until 1991 when, after several rumours about the band breaking up, they released Pink Bubbles Go Ape. The album was an utter failure commercially and critically, and soon tensions started to build up between the band members. The pop-influenced follow-up Chameleon, released in 1993, made the band lose most of their hardcore fans. During the Chameleon-tour, drummer Ingo Schwichtenberg fell ill due to personal- and drug-related problems, and was eventually forced to take a break from the band. Meanwhile the conflicts within the rest of the band had grown even worse, and the band decided to fire singer Michael Kiske.

Helloween returned in 1994 with former Pink Cream 69-singer Andi Deris as their new lead-singer, and Uli Kusch, formerly of Kai Hansen's new band Gamma Ray, on the drums, releasing their successful comeback Master of the Rings. However, in 1995 the band and its former members were badly shaken by the tragic suicide of original drummer Ingo Schwichtenberg, who never managed to recover from his illness. Dedicated to his memory, 1996's The Time Of The Oath re-established the band as one of the most popular European metal bands. Following another world tour, a double live album called High Live was released.

In 1998 Helloween released Better Than Raw, one of the band's heaviest albums since the full-length debut. A cover-album called Metal Jukebox was released in 1999. 2000 saw the release of The Dark Ride, a more experimental and darker album than their previous releases. Immediately after the following world tour, Helloween parted ways with guitarist Roland Grapow and drummer Uli Kusch who together formed Masterplan. Replacements were soon found in guitarist Sascha Gerstner (ex-Freedom Call, Neumond), and drummer Mark Cross (ex. Metalium) and Kingdom Come, currently in Firewind who was later to be replaced by Stefan Schwarzmann, former drummer of Running Wild and Accept. Another studio album titled Rabbit Don't Come Easy came in 2003 with a successful world tour following, including the bands first tour in the U.S. since 1989.

2005 saw yet another line-up change during the last tour as it became apparent that Helloween and Stefan Schwarzmann didn't share the same musical vision. As further noted by the band, he had some troubles at performing fast drum parts, so he was replaced by Dani Loeble, the previous drummer of German metallers Rawhead Rexx. Helloween's first studio album with the new line-up is called Keeper of the Seven Keys - The Legacy and was released in October 28th, 2005 in Germany, and November 8th in the U.S.A.. The story continues on tour, and Helloween has filmed and recorded already shows in Bulgaria , Tokyo and São Paulo for their forthcoming live-album/DVD. Which was released in early 2007. Also their newest studio album Gambling with the Devil saw the light in 2007 and was released in Germany on October 26th and October 29th in Europe.