Everyone knows there are some albums which any Metal Head should have listened to, such as Master of Puppets, Reign in Blood, or Rust in Piece, but I don't know. Maybe some people have missed the boat and don't know about everything they should. Have an album that you know any Metal Head NEEDS to hear.
I myself have found a boy going into 9th grade who needed a mentor, I stepped up and decided to learn him in the ways of Metal. He's loved everything I've given to him from Master of Puppets to Holy Diver, hell he even got to see Anvil when they came to town in April, which I had to miss. I want to give this boy, the last Metal fan at my school, which is filled with Lil Wayne and Bring Me the Horizon fans (not sure which disgusts me more), the Metal he needs. I figure calling on the combined knowledge of this group ought to be enough. We can use this not just for him, but for all of us, to get a better picture of the Metal we love, and I'm not talking just Thrash, I mean all of it from Black to Pirate to Trash to the Original stuff.
If you post an album feel free to give a description of it (be it song by song, a personal story behind it or just the Wikipedia summary)