The most influential heavy metal band to come out of Europe during the 1980s. By taking the hard-riffing and minor-key melodies handed down from metal masters like Judas Priest and Iron Maiden, then infusing them with the speed and energy introduced by the burgeoning thrash metal movement, Helloween crystallized the sonic ingredients of what is now known as power metal. The group hit their commercial peak in the late 1980s with the release of the two volume Keeper of the Seven Keys, which helped make them the benchmark by which most every power metal band is measured. Their meteoric rise was interrupted by internal strife and unfortunate business decisions, but Helloween took their hard-knock lessons in stride and continued to prosper well into the 2010's in the international metal arena on their own terms.