In the case of Metallica, “biggest metal band in the world” is almost an understatement. The were pioneers of the Bay Area wave of thrash metal in the early eighties, became absolutely huge with the 30-million selling Black Album in 1991, and almost split before their 2008 comeback. They are now the ultimate rock band with the most loyal fanbase, and millions of guitarists worldwide strive to replicate the solos of Kirk Hammett and James Hetfield’s amazing riffs.