My first metal album I had was Megadeth's Killing Is My Business. I was 11 at the time it came out. I was looking at records at a store, and this album jumped out at me. I had no idea who Megadeth were then, but I became so hypnotized by the album that I had to have it. So, I got money from my mom, and I bought the album. I was knocked on my ass in a major way. It was the most intense, and insane record I've heard in my life at that point. The riffs, the speed, Mustaine's snarled vocals. It was quite an experience. My life was forever changed on that day.
Before that the heaviest things I heard were things like Motley Crue, Judas Priest, Iron Maiden, and Ratt from watching MTV, and listening to the radio. Megadeth surpassed that stuff in more ways than one, haha.