“The Amityville Horror” was based on a book by Jay Anson, published in 1977, and “Amityville II: The Possession” was based on a book by Hans Holzer called “Murder in Amityville” published in 1979. Both these books took the demonic elements and went to town with it. The latter publication explained how demonic forces compelled Ronald DeFeo to kill his family and told how he hadn’t been acting out of free will.
Dubbed “Jaws with Claws” when it was released; “Grizzly” is not exactly original. I think every reviewer who’s covered the film has pointed out it’s unabashed similarity with “Jaws” (1975) and of course “Grizzly” is a rip-off of that classic film. But on it’s own lo-fi terms it’s a terrific B-movie that still entertains to this day.