Gaston from Beauty and the Beast may not be the obvious choice for most terrifying Disney villain, but this is a great argument as to why he is just that. It’s no secret that Gaston is a misogynistic bully, but what is so terrifying about him is that he could be anyone in the world. He’s a realistic villain and what’s so insidious about him is that society loves him for it. This post explains this further:
What is even scarier is that Gaston was based on a real person.