Metallica - Kill 'Em All is my all time favorite album and the one that got me into Heavy Metal
Besides that here is a list of some of my favorites
Tool - Ænima
Thin Lizzy - Thunder & Lightning
The Misfits - Earth A.D.
The Doors - Morrison Hotel
Death - Spiritual Healing
Pink Floyd - Wish You Were Here
The Prodigy - Music For The Jilted Generation
Aphex Twin - Selected Ambient Works Vol II
Devin Townsend - Accelerated Evolution
Frank Zappa - Joe's Garage Acts II & III
Megadeth - Rust In Peace
Electric Wizard - Dopethrone
Sleep - Dopesmoker