Formed in 1983 by guitarist/vocalist Dave Mustaine and bassist David Ellefson, Megadeth became one of the most acclaimed and successful thrash metal outfits of their era and beyond. Part of the "big four" of the genre along with Metallica, Anthrax, and Slayer, the group expanded on the typical metal blueprint by speeding up the tempos and putting an emphasis on lightning-fast technical guitar skills. Mustaine's nihilistic lyrics and the band's unrelenting musical attack resulted in a series of early thrash classics.