The Slitheen familynote (Ninth Doctor)
The first recurring aliens original to the revitalized Doctor Who franchise, the Slitheen are basically a family of Used Car Dealers and Con Men. IN SPACE! Their family hails from the planet of Raxacoricofallapatorius, where most of the family has been sentenced to death for being rather annoying and kinda evil. Unlike most alien baddies, they're a crime family, not an Always Chaotic Evil species the other Raxacoricofallapatorians are, according to the Doctor, rather peaceful. While they mainly only showed up during the Ninth Doctor's tenure (and an unidentified Raxacoricofallapatorian cameoing at the end of the Tenth's), the Slitheen also made it over to The Sarah Jane Adventures, where a rival family, the Blathereen, is often mentioned, and two Slitheen-Blathereen (orange-skinned Raxacoricofallapatorians) appear, along with a strange dark green-skinned Raxacoricofallapatorian. Perhaps the most unique feature about the Slitheen is their habit of skinning humans and using said skins as disguises.
- Affably Evil: They're only doing their business, after all, even if said business does involve destroying entire planets. Besides, hunting and killing are a trait of their species. They can't really help that, and they're pretty polite until you upset them.
- All There in the Manual: Most notably covered in Doctor Who Files 3: The Slitheen.
- Always Chaotic Evil: Subverted. We're led to believe they're just another invading species, but they're actually a criminal syndicate. Raxacoricofallapatorians are rather peaceful.
- Becoming the Mask: Both Blon Fel-Fotch Passameer-Day Slitheen and her brother who impersonated Oliver Charles/Asquith appear to suffer from this. The former is horrified after she realised she's gone native after six months amongst the Welsh, while the latter regrets having to ditch his old skin suit, as he got to have "a wife, a mistress and a young farmer".
- Bizarre Alien Biology: They're made of calcium, able to smell fear and pheromones produced by humans, and can expel poison through their fingernails (via darts) or their breath. Due to their biochemistry, they also have a severe allergic reaction to vinegar (although it is implied that this only happens because the compression fields they use to hide in weaken their body's structure so much).
- Costumes Change Your Size: Justified with their technology, allowing them to fit inside of their tinier human disguises.
- Cruel and Unusual Death: The reason Slitheen don't go home. Their method of execution involves them being lowered into a vat of acid, which causes their innards to fall out, while the Slitheen's still alive. Then the acidy-slitheeny soup is drunk afterward.
- Egomaniac Hunter: The Slitheen family, at least, enjoy hunting and treat it like a ritual.
- Even Evil Has Loved Ones: They're a crime family that legitimately cares about each other after most of them are killed in their debut, Blon cries about her lost loved ones in a later episode.
- Evil Has a Bad Sense of Humour: They tend to act like evil, overgrown kids. Apart from the fart jokes, their idea of a fake alien is to take an ordinary pig, perform gruesome surgery on it and then stick it in a spaceship.
- Evil Plan: The family Slitheen seems to be rather good at vile schemes to enrich themselves. It's just that they don't count on the Doctor showing up, or Sarah Jane Smith.
- Evolutionary Retcon: Following their appearance in Series 1 of the revival, new costumes were constructed for the Slitheen's reprisal in The Sarah Jane Adventures, giving them more expressive faces which enabled them to bare their teeth, making them appear somewhat more fearsome. It were these costumes that were used when the species eventually came back to the main show for a cameo in "The End of Time".
- Exposed Extraterrestrials: When they're not in their human suits. Lampshaded with dialogue about it being traditional to hunt naked.
- Face Stealer: Along with the rest of your skin.
- The Family That Slays Together
- Fat Bastard: In their human disguises, as the eight-foot-tall Slitheen have to use the skins of overweight people for disguises.
- Gasshole: Not naturally, but squeezing into their human disguises requires a "gas exchange" that results in this. In their first appearance it is implied that this is an unintentional side-effect or the result of equipment malfunction, when the one impersonating Margaret Blaine says they've "got to fix the gas exchange", although this never comes up again.
- Hannibal Lecture: Margaret/Blon in "Boom Town" while trapped in the TARDIS, tries to guilt the heroes into releasing her. Jack says not to answer back, "... it's what she wants."
- Hunting the Most Dangerous Game: The Slitheen family, at least, really like hunting humans.
- Kill and Replace:The Doctor: You're pleading for mercy out of a dead woman's lips.
- Killed Offscreen: In just about any story where the Slitheen appear, the humans they've disguised themselves as will have been killed some time before the story begins.
- Lady Looks Like a Dude
- In Titan Comics' "Doctormania", Rose is scandalised to learn that a Slitheen who had been posing as the Ninth Doctor is actually female, quipping that Captain Jack would love her.
- In "Death on the Mile", of Big Finish's Lady Christina, a female Slitheen disguises herself in the skin of a male human.
- Only Known by Their Nickname: Members of their species are often referred to as "Slitheen", after the infamous crime family that hails from Raxacoricofallapatorius. The Doctor mentions that the other members of the species are peaceful and implies they're somewhat irritated by the Slitheen sullying their good name, which might explain why all the Slitheen family have been been sentenced to death on their homeworld.
- Overly Long Name: Raxacoricofallapatorius.
- Psychopathic Manchild: They often come off as sophomoric and immature given their amusement with the side effects of their Face Stealer technology.
- Rogues Gallery Transplant: After being introduced in the first season of the revival series, the Slitheen effectively migrated to The Sarah Jane Adventures, making more appearances there than in the show that birthed them.
- Toilet Humour: The best way to spot a disguised Slitheen? They fart. A lot.
- To Serve Man: Though not made clear in their first appearance, it is established that the Slitheen are not above eating people. In The Sarah Jane Adventures adventure "The Gift", the Slitheen-Blathereen intend to have Sarah Jane for dinner. In the Big Finish story "Madquake", a pair of Slitheen go on a human hunt with the explicit intention of catching and eating Tegan and Nyssa, since it's been so long since their last hunt they've forgotten what humans taste like.
- Weaksauce Weakness: Vinegar. Go figure.
- Adult Fear: The Slitheen couple in "The Lost Boy" embody this trope horrifyingly well. Working alongside Mr. Smith, they gaslight Luke into believing he's actually their normal human son, forging evidence that allows them to take him away from Sarah Jane.
- Exposed Extraterrestrials: When not in human suits.
- Fat Bastard: They kill fat humans and use the skins as disguises, because their body compressing technology only compresses them enough to fit. Except in The Lost Boy, where two of them use the skins of a rather skinny couple to pull off their plan, thanks to newer, more advanced compression technology.
- Hunting the Most Dangerous Game: They love killing humans.
- Palette Swap: The Slitheen-Blathereen from The Gift are brownish-orange, compared to the more yellow-green Slitheen.
- Also in The Nightmare Man, an unnamed Slitheen is shown to be a much darker shade of green than the others shown, leading some to believe that he is actually from another Raxacoricofallapatorian family.
- Rogues Gallery Transplant: After appearing in only two Doctor Who stories, they transferred over to Sarah Jane's Rogues Gallery permanently.
- Toilet Humour: A major part of their character humour. But absolutely averted in The Lost Boy.
- Took a Level in Badass: "The Lost Boy" ramps up their threat level considerably, which sees them remove their comedic aspects by shedding their previous weaknesses of only being able to disguise themselves as fat people and bypassing the pesky gas exchange. They can effectively disguise themselves as humans even in private and put Luke in a terrifyingly vulnerable position.
- Villain Decay: Zig-Zagged. Their threat level is quite inconsistent, with their cameo appearances seeing them get dispatched easily by the heroes. However, they are still extremely cunning, savage, 8-foot tall monsters and many later episodes retain their intimidation factor.
- Weaksauce Weakness: They explode upon contact with vinegar, because they're made of calcium.
Blon Fel-Fotch Passameer-Day Slitheen, aka Margaret Blaine (Ninth Doctor)
A member of the Slitheen family who came to Earth as part of their plan to destroy the planet, before being the only survivor by means of an emergency teleport when 10 Downing Street was blown up. Afterwards, she set herself up as the Mayor of Cardiff as part of a plot to use the time-space rift running through the city to power her escape vehicle, which would have destroyed the planet in the process.
- Ascended Extra: Originally she was just one of the four main Slitheen antagonists of "Aliens of London", but "Boom Town" explores her individually.
- Going Native:"London doesn't care! The southwest coast could fall into the sea and they wouldn't notice! Oh God help me, I've gone native."
- Go into the Light: While threatening Rose, the Doctor uses the light from the heart of the TARDIS to distract her. It consumes her and reverts her into an egg.
- Go-Karting with Bowser: "Boom Town" gives us a dramatic example as Blon is forced to hang around Cardiff and eat dinner with the Doctor only because he has her on a literal leash.
- Go Out with a Smile: When she realises that the TARDIS can give her a second chance at life, she graciously thanks the Doctor while positively beaming.
- Ignored Epiphany: She seems to gradually warm up to the idea of reformation while hanging around with the Doctor, but ultimately still tries to blow up Cardiff to facilitate her escape.
- Mayor Pain: She sets herself up as the mayor of Cardiff as part of her escape plan, which would have destroyed the planet as collateral damage.
- Pet the Dog: Discussed. Blon spares a snooping journalist after discovering that she was pregnant, and the Slitheen brings up this instance of mercy as an example of her ability to change positively when she's trying to convince the Doctor not to execute her. The Doctor dismisses it as a momentary glimmer of empathy that all mass murderers experience before going right back to plotting the slaughter of millions. Of course, he can talk from experience.
- Raise Her Right This Time: She is reverted into an egg by the Heart of the TARDIS, and is returned to Raxacoricofallapatorius to be raised by a new family.
- Shut Up, Kirk!: Delivers a cutting, concise one to the Doctor when he begins ranting about how sparing a victim occasionally is an unrepentant killer's way of justifying themselves, not a sign of reformation.Margaret Blaine: Only a killer would know that.
- Sole Survivor: Due to her one-person emergency teleport, she was the only one of the Slitheen who came to escape the destruction of 10 Downing Street.
- Synchronization: She and shady Torchwood agent Suzie Costello in the aptly-named Big Finish audio Sync, due to alien phlebotinum.
- Villainous BSoD: Has an extended one over the course of "Boom Town" after sparing a pregnant woman and being forced to bargain for her life with the man who killed her whole family.
A young member of the Slitheen family. He first appears in Revenge of the Slitheen disguised as Carl to help his father and uncle in their plot to turn off the Earth's sun. When their plan backfires, Korst and his father beg for Sarah Jane's help. Though Sarah Jane tries to help them, she fails. Korst's father is killed in the resulting explosion and Korst blames her for his father's death. He reappears in The Lost Boy, disguised as Nathan Goss.
- Creepy Child: He has a gleefully sadistic personality. Keep in mind, he's a psychotic alien who disguises himself in skinsuits of young boys he has killed.
- Even Evil Has Loved Ones: He dearly loved his father.
- Evil Counterpart: Like Luke, he's a socially awkward Teen Genius with alien origins. He resembles what Luke could have turned out like if he was raised by the Bane.
- Hunting the Most Dangerous Game: In his first appearance, he is obsessed with the opportunity to hunt humans.
- Teen Genius: He's considered a child prodigy and performs telekinesis experiments for the Pharos Institute while disguised as Nathan Goss.
- You Killed My Father: Korst blames Sarah Jane for his father's death.