C.H.U.D.

CHUD (Cannibalistic Humanoid Underground Dweller) is a 1984 horror film about carnivorous mutants in the sewers of New York City. Street people begin to disappear and the police start to take notice. The eponymous creatures become bolder and come out to drag away more noticeable people, but the Nuclear Regulatory Commission covers up their existence until the last minute.

The movie spawned two sequels of questionable relation to the first.

Tropes used in C.H.U.D. include:

Absurdly Spacious Sewer: Though New York actually has these.
Beneath the Earth: It is a movie about mutants dragging people into the sewers.
Big Applesauce
Body Horror: The monsters are horribly mutated humans. One scene takes it further, with the chud's neck stretching to a giraffe-like length for no explained reason.
Crazy Homeless Person: Averted and played straight. Many sympathetic and intelligent street people are shown. However, the chuds were homeless people and we get to see a couple in mid-transformation.
Disposable Vagrant
Eye Lights Out: The chuds' eyes lose their radioactive glow when they die.
Glowing Eyes of Doom: Perfect for looking creepy while crawling out of the sewer.
Hey, It's That Guy!: John Goodman is one of the cops at the diner.
I'm a Humanitarian: The chuds seem to prey primarily on humans, even leaving the body of a dog dragged down with one of their victims uneaten.
Initialism Title
Nuclear Nasty: The heroes can track the things with a Geiger counter.
Obstructive Bureaucrat
The Reveal: C.H.U.D. does not stand for Cannibalistic Humanoid Underground Dweller. It stands for "Contamination Hazard Urban Disposal" and the agency coverup.
Shout-Out: The Simpsons give a memorable one when Homer explains why he hates visiting New York City:

Homer: ...and that's when the C.H.U.D.s came after me."

Was Once a Man: The chuds were originally homeless people who were mutated by radioactive waste left in the sewers.