Celtic Frost was an influential metal band from Zurich, Switzerland. They are known for their heavy influence on the extreme metal and gothic metal genres. The group was first active from 1984 to 1993, and re-formed in 2001. Following Tom Gabriel Fischer's departure in 2008, Celtic Frost decided to break up again. Celtic Frost's frontman, guitarist and singer Tom Gabriel Fischer, adopted the alias Tom Warrior. With Steve Warrior on bass, he formed one of the earliest extreme metal bands, Hellhammer, in 1982. Steve Warrior was later replaced by Martin Eric Ain - also a pseudonym.