Paranoid (1970)

Tony Iommi's heavy, sludgy riffs and Geezer Butler's driving bass lines turned Birmingham blues rock into something darker and heavier, and much of metal grew from here. The title track is the fast, punchy way in; Iron Man and War Pigs show the slow, crushing side. Ozzy Osbourne's distinctive, melodic vocals keep every song instantly memorable for a hard-rock fan.