Helloween is a German heavy metal band formed in 1984, known for pioneering the power metal genre. Their music features fast tempos, melodic guitar riffs, and fantasy-themed lyrics. The band gained popularity with their albums like "Keeper of the Seven Keys," which helped define the sound of power metal. The band's lineup has changed over the years, but key members include Michael Kiske and Kai Hansen. Helloween has influenced many other bands and continues to tour and release new music, maintaining a dedicated fan base worldwide. Their energetic performances and catchy melodies have solidified their place in metal history.