11. ‘Where Is the Line’ (2004)
Who needs guitars to be metal? Who says acappella can't be cool? The Vikings invented heavy metal centuries ago, and Björk taps into her ancestral headbanging on this aborted single from ‘Medulla’, an album constructed solely from the human voice. The guttural beatboxing of Rahzel is chopped and layered into something that gets our devil horns in the air every time.