King Crimson - Discipline
By a god damn mile the best album from 1981 according to me. I don't consider this metal but this counts anyhow, because it rocks and it rocks hard, much like a 6am erection.
Ozzy Osbourne - Diary of a Madman
I'll be real honest and say that Ozzy's solo career, on the whole, fucking sucks. But the title track here alone is so amazing, that it almost makes up for a lot of his foolishness. Almost.
Rush - Moving Pictures
I don't even like this god damn band but at least I recognize that this album is pretty stellar. The Camera Eye, YYZ, and Tom Sawyer are all great.
Not metal but some of my all time favoUrite albums came from 1981:
The Residents - Mark of the Mole
Siouxsie and the Banshees - Juju
Frank Zappa - You Are What You Is