I have a few favorite “villians”, although a couple of them weren’t too bad, like the Dalek Human or the CatKind. So I’ll go with 3 of them.
The Midnight Entity was terrifying because not even the Doctor knew what it was, and he also didn’t have Donna to help him. It was the first time everyone started not trusting the Doctor, which I thought was terrifying… and yet pretty fucking awesome. Made for a great episode at least. Also, DO YOU SEE THAT PLANET? It’s BEAUTIFUL!
Raxacoricofallapatorians. Slitheen. I hated these guys at first. But they’re just SO DAMN COOL LOOKING. Also, Margaret was pretty cool. I was happy she let that pregnant reporter go. Also, the story for both of those episodes were great.
Vashta Nerada were terrifying as all fuck. I didn’t want to go to bed after I saw those episodes. And I’m 18. They are based off of a regular Human fear, the dark. Which is pretty damn clever. Even though that’s what the writers always do. BUT STILL.