Megadeth /ˈmɛɡəˌdɛθ/ is an American heavy metal band from Los Angeles, California, that was formed in 1983 by Dave Mustaine and David Ellefson. The band has since released 14 studio albums. A pioneer of the American thrash metal movement, Megadeth rose to international fame in the 1980s and is ranked as one of the "Big Four of Thrash" along with Metallica, Slayer and Anthrax, who were responsible for creating, developing and popularizing the thrash metal sub-genre.

Over the band's 30 active years, more than 20 different people have officially performed as part of the group, with Mustaine being the only constant member. Megadeth is known for its distinctive, technical instrumental style that often features dense, intricate passages and trade-off guitar solos, and for recurring lyrical themes including politics, war, addiction, personal relationships, and religion. The band has sold over 50 million records worldwide with six consecutive albums being certified platinum or multi-platinum in the US, according to the band's official website. Peace Sells... but Who's Buying?, So Far, So Good... So What!, Rust in Peace, Youthanasia, and Cryptic Writings all achieved platinum status, the band's fifth and most successful record, Countdown to Extinction, sold multi-platinum, and the album Risk achieved gold certification. As of 2013, Megadeth has received eleven Grammy nominations.