Humongous

A woman's son, born after a traumatic assault, grows into a monstrous killer haunting a group of shipwrecked teenagers stranded on his island.

Humongous is a 1982 horror thriller movie directed by Paul Lynch, starring Janit Baldwin, Janet Julian, David Wysocki. It holds an IMDb rating of 4.8/10 from 2,390 votes and runs 1h 37m.