Megadeth? Artist name. Most famous album is probably Countdown to Extinction (1992). They, along with Metallica, Slayer, and Anthrax invented Speed Metal / Thrash Metal in the 1980s.
South of Heaven is by Slayer. Slayer’s most influential album was Reign in Blood (1986).
Dave Mustaine is the singer and guitarist of Megadeth, and widely considered to be extremely skilled.