Megadeth is an American thrash metal band formed in Los Angeles in 1983 by vocalist and guitarist Dave Mustaine after he was fired from Metallica. Known for their technically complex guitar work and politically charged lyrics, they became one of the "Big Four" thrash metal bands alongside Metallica, Slayer, and Anthrax. Their breakthrough album "Peace Sells... but Who's Buying?" (1986) established them in the underground metal scene, while "Rust in Peace" (1990) is considered their masterpiece.