I would say that Metallica really was the first band I really loved + it got me into metal...I must of been around 15 when I turned into a metal fan...
My dad let me listen to Six Feet Under when I was in the 6th grade and i have not looked back.
Oh, mine was Sixx.A.M., Nikki Sixx's old side band, when I was 15 and had never previously listened to anything except Classical music and Gregorian Chant. I made a quick descent straight into death and black metal and never looked back.
Kiss - Destroyer !