Queensrÿche
Mötley Crüe
Skid Row (generally regarded as 90s heavy metal, but their first album was released in 1989)
Screaming Trees (again, generally 90s grunge, but they have albums released in the 80s)
Dream Theater (When Dreams and Day Unite was released in 1989 ;P)
Anthrax*
Metallica*
Megadeth*
Slayer* (*Big 4!)
Alice in Chains (Facelift was in the 80s, I think...)
Living Colour
King Diamond
Judas Priest (They had a few in the 80s)
Jane's Addiction
Frank Zappa had like 50 albums in the 80s... And in every other decade. He's a genius, though. He has so much music, and though a lot of it might go over your head (and believe you me, it will go over your head until you get used to it... I know what it's like)
ZZ Top
Sepultura (pre-death thrash, I guess? Kind of on the Slayer side of thrash, but a little further over the cliff)
Racer X
Mr. Big (Paul Gilbert was in Racer X and Mr. Big... If you know anything about guitarists, that should be reason enough to listen to both)
Dead Kennedys (Good Punk! Songs you may have heard: California Uber Alles and Holiday in Cambodia)
Yngwie Malmsteen
Twisted Sister
Rainbow