These are the 21 most popular metal bands according to Last.fm, so sorry if many important bands are missing #timeline #infographic #metal #heavymetal #metalfamily #metalhead #metaltok #blacksabbath #judaspriest #motorhead #ironmaiden #pantera #metallica #slayer #megadeth #sepultura #dreamtheater #rageagainstthemachine #tool #inflames #korn #rammstein #childrenofbodom #nightwish #systemofadown #slipknot #disturbed #bulletformyvalentine