Nightbreed (1990)

Aaron Boone (Craig Sheffer) is haunted by terrifying nightmares of a city of monsters. He goes to see a psychiatrist, Dr. Decker (David Cronenberg), for help. But what Boone doesn't know is that Decker is really a serial killer. Decker frames Boone to take the fall for his murders, and Boone is killed by the police. But Boone is brought back to life by the monsters of his dreams, the Nightbreed, who in turn join Boone in his quest to stop Decker from killing again.