Throughout Megadeth's many lineup changes, the two core members have been bassist Dave Ellefson and guitarist/vocalist Dave Mustaine (b. September 13, 1961), who is the band's official leader. Mustaine grew up in the suburbs of Southern California, where he was raised by his mother in a broken home; frequently, his mother left him to be raised by aunts and uncles, who never encouraged his musical inclinations and often belittled him for his fondness for heavy metal. In 1981, he formed Metallica with James Hetfield and Lars Ulrich. Mustaine spent two years with Metallica, developing a strong cult following in California's underground metal scene, before he was kicked out of the group, allegedly over his substance abuse. Immediately following his firing, he formed Megadeth with Ellefson. The pair recruited guitarist Chris Poland and drummer Gars Samuelson to round out the lineup.
For the next few years, Megadeth toured and gained a following, eventually signing with the independent label Combat in 1985. Later that year, the group released their debut, Killing Is My Business...And Business Is Good!, which received strong reviews, not only in metal-oriented publications, but also in mainstream music magazines. The album sold very well for an independent release, which attracted the attention of major record labels. By the end of the year, the group had signed with Capitol. Megadeth's first major-label album, Peace Sells...But Who's Buying? was released in the fall of 1986. Like its predecessor, Peace Sells was greeted to strong reviews and sales; it eventually went platinum.
Although the band's fortunes were on the upswing, Mustaine was beginning to sink deeper into drug abuse, as he began using heroin. Soon, his addictions began to effect his work. Many stories concerning his erratic behavior were circulating within the metal community, and they seemed to be proven correct when he fired both Poland and Samuelson before the recording of the band's third album; they were replaced by Jeff Young and Chuck Behler, respectively. The new lineup debuted on So Far, So Good...So What!, released early in 1988. So Far, So Good peaked at number 28 on the charts and went gold, and featured a cover of the Sex Pistols' "Anarchy in the UK."
In the years immediately following the release of So Far, So Good ... So What!, Mustaine was impaired by his drug addictions. In early 1990, he was arrested for driving under the influence and entered a rehabilitation program. By the end of the year, he was not only sober, but he had reconvened the band -- firing Young and Behler and replacing them with guitarist Marty Friedman and drummer Nick Menza -- and recorded Megadeth's fourth album, Rust in Peace. The record peaked at number 23 on the American charts and went gold.
Countdown to Extinction was released two years later, entering the charts at number two; the record went platinum, confirming that the band retained its audience in the wake of grunge. Megadeth followed the album with Youthanasia in 1994. Youthanasia entered the charts at number four and, like its predecessor, it went platinum. The following year, the group released Hidden Treasures, a rarities collection which entered the charts at its peak position of 90.