Ursula from The Little Mermaid
Before I even talk a word of shit about Ursula from The Little Mermaid, can I just point out that she was a badass, too? In terms of Disney villains, she had mad mojo. Rocking the “lesbian hair stylist” look from modern culture well before it got popular, and representing her “curves” with a certain level of, hmmm, je ne sais quoi, you cannot deny that she had a special something. The thing is, she was evil, and for many of us, she reminded us of a real person we knew.
For me, it was my Oceanography teacher from my high school years. Ironic, huh? She looked exactly like this woman, sounded like her, and much like Ursula, she seemed to think she was hot (which was terrifying to many of us). That level of personification helped her earn this spot.
But speaking in terms of genuinely terrifying, how about her final form? When she is looming over the horizon and purple storm clouds spit lightning behind her? That was the stuff of nightmare fuel. She was ALMOST as traumatizing as all the penises that the animators hid in the movie.