I have searched long and far to find actual legitimate websites to watch full movies without getting a virus or being overrun with ads and have found a few gems!
Here is a great site where you can watch FULL movies 100% FREE without needing to sign-up/register or anything! No catches!
Here are some great movies they have available for Halloween:
When A Killer Calls The Phantom of the Opera
Virus Atom Age Vampire
I Eat Your Skin Night of the Living Dead Vengeance of the Zombies
Monster & Creature Movies
Bride of the Gorilla