Xtro (1982)

Some extra-terrestrials aren't friendly.

Tony's father Sam, abducted by aliens three years earlier, returns to earth and seeks out his wife and son, but Rachel has since been living with Joe and the reunion is awkward. Joe doesn't trust Sam, and Rachel can't quite decide what her feelings are for her two men. Sam is not the same as when he left, and he begins affecting Tony in frightening ways.