Before Finland's Apocalyptica came along, no one knew how awesome metal sounded when rendered by cellos. With three classical cellists in their ranks, the group was formed in 1993 as a Metallica cover band before branching out into original material. Releasing studio albums at steady clip throughout the '00s, the four-piece has collaborated with fellow rockers like Gavin Rossdale of Bush and Corey Taylor of Slipknot. Their highflying fusion of metal, classical, world and folk music is one of the most unique sounds on earth.