Adewale Akinnuoye-Agbaje as Adebisi in Oz.
Alexander Skarsgård in Big Little Lies
David Tennant as Kilgrave in Jessica Jones
Mads Mikkelsen in Hannibal. So charming, so terrifying.
Hanzee Dent from Fargo. Dude was intimidating as fuck. I know the guy was a decorated war hero who would be unlikely to do something to you without being provoked (or ordered to) but shit, I'd be so scared of looking at him the wrong way and upsetting him somehow.
Frank Silva as BOB in Twin Peaks
Zachary Quinto in American Horror Story: Asylum [spoiler](#s "when he trapped Sarah Paulson in his basement, he was incredibly creepy")
Bryan Cranston in Breaking Bad has some terrifying moments.
Mads Mikkelsen in Hannibal.
John Lithgow in Dexter had some great moments.
People keep name-dropping Mads Mikkelsen from "Hannibal", but Richard Armitage as Francis Dolaryhyde was the one who was legitimately terrifying, especially in that scene with Chilton.
The Swede from Hell on Heels scares me. He's portrayed as an effective manipulator, but has pure evil in his heart. Hiow he toys with people is more primal than Hannibal, who is getting a lot of (rightful) praise here. Hannibal has his needs, but also struck me as a rational actor. The lack of emotion makes sociopaths scary, but the Swede showed sharp flashes of them. Where Hannibal exercises power over his victims, the Swede gets off by his victims empowering him.
I could sit down from Hannibal in a restaurant and make it through a meal feeling reasonably safe. Across from the Swede I would be waiting for him to lunge at any moment, probably after I picked up the check.
Freddy Highmore as Norman Bates. I thought he did a really good job during his freakouts in that show. He seemed very creepy, scary and just seemed devoid of all life in those moments.
Both Freddie and Vera did such a good job playing those roles.
Michael Emerson in Lost, particularly in Season 2 of the show when you don't know if he's a bad guy or just someone the survivors are holding against his will. That speech about what he would do if he was a bad guy was chilling.
I would be pretty intimidated running into Mads Mikkelsen for Hannibal or Gbenga Akinnagbe for Chris in The Wire.
Thinking of Bryan Cranston at the end of 4.11 "Crawl Space" still gives me chill over 6 years later.
Ramsay Bolton in Game Of Thrones, he was a terrifying villain with the amount of evil he had in him. I love his voice.
John Lithgow in Dexter and I hated the show after that season. He was terrifying.
David Thewlis as V.M. Varga in Fargo S3.
He seemed to know everything plus on more than one occasion I almost had to look away from the screen.
Marlo from The Wire
More recently, Perry (skarsgard) from Big Little Lies
I know this season gets a lot of hate, and I admit it's not the greatest season the show has had, but Kathy Bates as The Butcher in American Horror Story: Roanoke was terrifying! She saved that season tbh so thanks Kathy for scaring the shit out of me
Snoop from The Wire - she wouldn't have a problem killing me if she thought it necessary
Frank Silva as BOB in Twin Peaks is probably the only villain who made me feel truly uncomfortable.
Ray Wise in Twin Peaks' first two seasons hands down.
Frank Silva as BOB on Twin Peaks
I was 6 when Twin Peaks first aired and watched every episode. BOB was terrifying in a mundane way. He looked normal but then he'd leer at Laura or break into a rictus grin.
That scene of him climbing over the couch in the Palmer house will always fucking spook the shit out of me
Jesse Plemons as Todd in Breaking Bad was pretty terrifying.
Vincent D'Onofrio as Wilson Fisk/Kingpin in Daredevil on Netflix legitimately made me scared of him.