Every villain always threatens to return and wreak vengeance. No baddie worth their salt ever gets beaten and then announces they're going to retire. But some villains make an especially big noise about how they'll be back... and then, crickets. Here are 10 villains who made a big splash, and were never seen again.
Some of these villains were planned to come back, but there was a change of plans. Some of them were introduced with a fanfare, and then just sort of slipped through the cracks. And some of them... just didn't work out, for one reason or another. Also, a few of these did get a continuation in tie-ins, like comics or whatever, but not in the actual series they appeared in.
1) Mind-Controlling Parasites in "Conspiracy," Star Trek: The Next Generation
Remember when Starfleet was taken over by a bunch of alien body-snatchers who managed to send off a homing signal before being defeated? A homing signal that would tell their pals back home where to find Earth? Well, you might, but TNG sure didn't.
2) Bureau 13 in "A Spider in the Web," Babylon 5
This was a mysterious organization of Psi-Corps operatives, that was introduced with a ton of ongoing mysteries and sticky questions. And then Bureau 13 vanished back into the shadows. Creator J. Michael Straczynski explained that this was because the name Bureau 13 turned out to be already used by a role-playing game, "Stalking the Night Fantastic." He adds: "We hadn't heard of the Bureau 13 game when we did the episode, it was just something we came up with 'cause it sounded neat. Later, we found out there was a game by that name. At which point I decided that it wouldn't be appropriate to use that name again, and had a good conversation with some folks at the game company about it. There was no problem, I just didn't want to walk on their turf intentionally or otherwise."
3) The Hands of Blue guys in "Ariel," Firefly
What was up with those guys? Why did they need to wear blue gloves? Who were they working for? You might have expected them to have a big role in Serenity, given that they were searching for River Tam and played a big role in her story — but apart from a brief glimpse of them in one other episode, they were never seen on screen again. They have gotten a bit more development in a tie-in comic, however.
4) Bilis Manger in "End of Days," Torchwood
Appearing in the first season finale of Torchwood, the mysterious Bilis Manger is a sinister guy who wants to raise mega-Satan on Earth and stuff. This ally of Abaddon can jump through time at will, plus he's a wily manipulator — making him a formidable opponent for Captain Jack and his crew. So you would think he'd play a huge role in the show's second season, right? Nope. He did get included in one tie-in novel and a comic, though.
5) Dark Energy in Mass Effect 2
You deal with "Dark Energy" as a threat in one mission in Mass Effect 2, and it's built up as a potential concern for later... and then it's never seen again. Drew Karpyshyn, lead writer of Mass Effect and Mass Effect 2, who then left Bioware, explained that one scrapped idea for the ending of Mass Effect 3 involved trying to stop the spread of Dark Energy, because it could hasten the end of the universe. But this was abandoned, and Dark Energy was never mentioned again.
6) The Valeyard in "Trial of a Time Lord," Doctor Who
Probably the most famous of Doctor Who's unreturned villains, the Valeyard is "an amalgamation of the darker side of the Doctor's nature" from between his twelfth and final regenerations. Since he was probably supposed to be created by now, his absence is particularly notable, and despite appearing in a bunch of non-television stories, it seems unlikely that he'll return on screen. He did get namechecked in passing in "The Name of the Doctor."
7) Logan St. Clair in "Double Cross," Sliders
Logan was a double of Quinn's (except for being female), and she was bad news. She murdered her world's Arturo because he discovered that she was planning on using sliding technology to steal resources and hold other worlds hostage, and when the Sliders gang finds out what she's up to, she tries to kill a few other people too. Despite getting an open ending—she ends up sliding randomly too and she may have the ability to find them—she never appeared again.
8) The Wrath in "The Player on the Other Side," Batman Special #1
The Wrath is supposed to be the equal and opposite version of Batman — a darker version of the Dark Knight whose criminal parents were killed by the police. Instead of fighting crime, Wrath uses his Batman-like skills to fight the law, and he's Batman's counterpart in every way. Mike W. Barr and Michael Golden put a lot of effort into making the Wrath appear to be a new potential arch-nemesis for the Caped Crusader. In this special anniversary story, Bats is pushed to his limits to defeat someone who has all the same skills, albeit with a sillier outfit. And then at the end of the issue, Wrath is apparently killed... but we don't really see a body. We also don't see the Wrath again, either. Decades later, the comics introduced Wrath II, the Wrath's former apprentice who's taken on the mantle. And there are alternate-universe versions of the character. But the Wrath, as introduced in Batman Special #1, remains a one-off.
9) Experimenting Aliens in "Schisms," Star Trek: The Next Generation
We never knew a lot about these guys, either about the reasoning behind their decision to abduct and experiment on the Enterprise crew or about whether they managed to get off a probe at the end of the episode. The ending is intentionally left open, but after seeing the look of the aliens (producer Brannon Braga described as looking like "fish monks") the producers decided to leave them as one-offs.
10) The Movellans in "Destiny of the Daleks," Doctor Who
Terry Nation created so many villains for Doctor Who that were supposed to stick around, but turned out to be one-shots. Back in the 1960s, he created the Voord, who were supposed to be the next Daleks and received a huge merchandizing blitz before falling through — and also the Mechanoids, who were supposed to be the Daleks' new arch-enemies. He tried again to create arch-enemies for the Daleks in 1979 with the Movellans. These very stylish androids were supposedly involved in an intergalactic war with the Daleks for years—which you would think would make them pretty important players, but apparently not, because they just sort of faded away. Maybe it had something to do with wearing their power packs on their belts for anyone to disable?
Thanks to Steve Alloway, Bryant Francis, Franklin Harris, Laurel Amberdine, UkuleleDan, Simone Davalos, Devindra Hardawar, Tim Ford, Meghan Bee, Kitty Niclaian, Noah Diamond, Kal Cobalt, Dave Sinclair, Jason Goldman, Oscar Bermeo, Thomas LaRue, Michael Weyer, Eric Del Carlo, Christopher Nickolas Carlson, Chris Braak and everybody else who helped with this article!