Not that anybody’s REALLY in charge–but as the OP, I say “nope.” I was looking for most chilling villains who appeared only ONCE.
I liked the Evil Clown from an old Voyager episode. Basically, a bunch of people hooked themselves together in a communal mindlink/virtual reality, and the Clown is a rogue manifestation of their subconscious, and knows everything they know and think. It had been torturing and even killing them with their worst fears for years.
:smack: OOps. I missed that about the 1 time only. Sorry…
That was one of the few Voyager episodes that actually had a dramatic, understated and entirely unpreachy ending, which was downright refreshing.
Well, it may or may not have been a two-part episode so I’m not sure this qualifies (?), but Bruce Willis played a horrible, fucked-up, wife-beating bad guy on Miami Vice once. He was pretty damn menacing. You don’t get to see him play bad guys much, but he’s really good at it.
And they’re almost the only really villainous X-Files villains who were one-offs. Eugene Tooms? Repeat. Donnie Pfaster? Repeat. I suppose you could make a technical exception for Robert Modell (“Pusher”)
because in his second episode he wasn’t actually the villain
How about the Flukeman from “The Host”? Or don’t monsters count as villains?
I think he counts: he’s a one-off who was so good they brought him back later for a whole movie.
Hans Gruber from Die Hard.
What an evil, mean, educated, polite, sneaky bastard who wants to kill several hundred people under the guise of terrorism so he can be “sitting on a beach earning twenty percent.”
Tim Roth’s character in “Rob Roy” ?
Michael Madsen’s character in “Reservoir Dogs” ?
I remember that one. It kept me watching another year or two. Truly villainous.
Oh, yes, HIM I remember. Played by what’s-his-name from spinal time/lavern & shirley…michael something…annette o’toole’s husband. That clown was even creepier than your average clown.
Michael McKean?
The Peacock Family was who I came in to mention, not at all surprised somebody beat me to it. That was one disturbing episode. I think it was the Johnny Mathis music that really sent it over the top.
Sticking to TV shows (which is how I read the OP, not that I haven’t strayed from an OP before), Patrick Macnee’s appearance as Count Iblis on the original Battlestar Galactica was pretty cool. It’s rare that Satan himself (or someone like him) appears on a non-comedic episodic TV. If only the Battlestar folk had known that al-Iblis is an Arabic name for the devil… dumbasses. (He was actually in 2 episodes, but it was a 2 parter, so I’m counting it as a single appearance.)
John Hanna’s appearance on Carnivale as essentially a pimp for a town of zombies was pretty eerie. Also eerie on the same series was Brother Justin’s inadvertent patron who, it was discovered, was a pedophile.
Wait. Why do you say that they didn’t? Or am I being whooshed? It would seem to me that their use of the fairly uncommon name would imply that they were aware of it.
I’m talking about the characters on Battlestar Galactica, not the producers and writers (who most certainly knew about it- there is also a good deal of Mormonism in the series).
The female lead in Body Heat. Very bad woman.
I cannot hear that song without getting creeped out. 
After I came up with the Peacocks, I thought about it, and I came up with Tooms and Donnie and discarded them. Donnie would have been a great one, but alas, they gave him a second episode. I’ll also submit (though I can’t remember his name) the bad guy from “Unruhe.” Eeeeeeek.
Kathleen Turner, who can be deliciously evil just about anytime she sets her heart to it.
I didn’t know McKean was actually married to O’Toole; I thought Fabulous Creature was just remembering an episode of Law & Order when they played a married couple:
She’s angry over a time when he slapped her around, so she leads him to believe she’s having an affair, subtly manipulates him into killing her “lover” and cheerfully watches him get dragged off for a life sentence. Brrrrr… and it makes her a good nomination for this thread.
Sorry – I see now that I violated the OP by referencing a movie instead of a TV show, as requested. Obviously, movies would need their own thread. What a maroon.
Aaaaaaaaaaaaaaaaah.