They Live must be John Carpenter's masterpiece. It isn't the most polished movie, with limited special effects and acting straight from the pro-wrestling circuit, and locations that may be LA, but look more like generic Canadian city. But 1) Pro-wrestler/actor Rowdy Roddy Piper has come to kick butt and chew gun, and he's all out of gum, and 2) the butts that he kicks are the most vicious incarnations of evil: republicans from space.
The plot is simple. Drifter-construction worker Piper finds a pair of sunglasses that reveal the truth: Magazines and billboards just say "Obey", "Consume" and "Stay Asleep". Money is just white paper with the words "Your God" printed on them. And some people, the rich and powerful, are not human. Roddy's response is cool and measured. He starts blowing them away.
Best scene, other than the kicking butt and chewing gum line above (a Roddy Piper ad-lib), has Piper trying to convince Keith David to try on the magic sunglasses by whooping him. David whoops him back. They exchange whoopings for a long time, some of them pretty realistic, some of them right out of the pro-wres ring. All enough fun so that you hardly wonder why he doesn't just look through the damn things and save everybody some pain.