David Scott Mustaine (born September 13, 1961) is an American guitarist, singer-songwriter, actor, and author. He is best known as the co-founder, lead vocalist, guitarist, and primary songwriter of the American heavy metal band Megadeth, as well as the original lead guitarist of the heavy metal band Metallica.

In 1981, Mustaine disbanded Panic and joined Metallica as the lead guitarist. Metallica's drummer Lars Ulrich had posted an ad in a local newspaper, The Recycler, looking for a lead guitarist. In his own words, Mustaine remembers his first meeting with James Hetfield and Lars Ulrich: "I was in the room warming up and I walked out and asked, 'Well, am I gonna audition or what?', and they said, 'No, you've got the job.' I couldn't believe how easy it had been and suggested that we get some beer to celebrate."

Metallica began recording their first album titled "Kill 'Em All" in 1983 but Mustaine's tenure with Metallica was short-lived. Before the album was completed, Brian Slagel, owner of Metal Blade Records, recalled in an interview: "Dave was an incredibly talented guy but he also had an incredibly large problem with alcohol and drugs. He'd get wasted and become a real crazy person, a raging megalomaniac, and the other guys just couldn't deal with that after a while. I mean, they all drank of course, but Dave drank more… much more. I could see they were beginning to get fed up of seeing Dave drunk out of his mind all the time."

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