Re-Animator (1985)

After an odd new medical student arrives on campus, a dedicated local and his girlfriend become involved in bizarre experiments centering around the re-animation of dead tissue.

Or as they put it in American Beauty... that movie where "the body is waIking around... carrying its own head, and then the head goes down on that babe."

I mean, that's all you really need to know.  I don't even need to say anything else to justify this placement.

Aliens (1986)

Decades after surviving the Nostromo incident, Ellen Ripley is sent out to re-establish contact with a terraforming colony but finds herself battling the Alien Queen and her offspring.

One of the greatest sci-fi movies of all time.  One of the greatest action movies of all time.  And one of the greatest horror movies of all time.  That's a goddamn trifecta, if there ever was one!

Oh, and it has a serious case for being the greatest sequel in the history of cinema.  No big deal.

Seriously though, this is one of the rare movies where the sequel outclasses the original in every way.  Not to take anything away from the original Alien, but this thing cranks everything up to 11.  And I mean everything.  It has such a classic ensemble cast, with so much quotable dialogue, so many great setpieces, so many great effects, and such amazing sound design.  It's really a perfect film.  They could have forever ended the franchise here, and we all could have died happy.

And if you're a gamer who somehow hasn't seen this, just know it may be the most influential movie in history, as far as gaming goes.  So you should probably do something about that.  Just saying.

Night of the Creeps (1986)

Alien brain parasites, entering humans through the mouth, turn their host into a killing zombie. Some teenagers start to fight against them. [really IMDB?  That's the worst description I've ever read on your site]

So much fun.  Part 1950s alien creature feature, and part splatter zombie fest, this movie is all awesome.  Tom Atkins is gold, the young leads are great, the practical effects are great, the comedy is hilarious... it's another perfect 1980s horror comedy.  Maybe not as great or iconic as American Werewolf, but damn good nonetheless.

It also heavily influenced another later movie that I love even more.  If you're a horror guy you should know exactly what I'm talking about.  It will show up in a couple weeks.