Megadeth is an American heavy metal band from Los Angeles, California. Guitarist Dave Mustaine and bassist David Ellefson formed the band in 1983 shortly after Mustaine's dismissal from Metallica. Along with Metallica, Anthrax, and Slayer, Megadeth is one of the "big four" of American thrash metal, responsible for its development and popularization. Their music features complex arrangements and fast rhythm sections, and lyrical themes of death, war, politics, and religion.