Nasty Party

A person or group of people are invited to a social gathering—a party, banquet, or any other form of get-together. However, it's just an excuse to get them all together and kill them.

An Old Dark House is an ideal place to pull this off.

In Real Life, this is literally one of The Oldest Tricks in The Book—it's been played countless times since the beginning of history. It has also always been considered as an especially ruthless and evil thing to do, as it is the ultimate violation of Sacred Hospitality—transgressing against the latter is frowned upon even by warlike cultures and usually crosses the Moral Event Horizon. It's a classic nevertheless, because, after all, it is also very effective and convenient.

A subtrope of Lured into a Trap. Compare Reunion Revenge, A Fete Worse Than Death, Board to Death and Ten Little Murder Victims.

Nothing to do with the Conservative Party of Great Britain, occasionally known as "the nasty party" by its critics. Also not to be confused with Those Wacky Nazis.

Anime and Manga

 * Lupin III: "Return of Lupin III" (the first episode of the second series) features the gang—including the Inspector Zenigata—reuniting after they all get invitations to a cruise ship. Unfortunately, it turns out to be a ploy by a former criminal mastermind who's out to get revenge on Lupin.
 * A variation of this is shown in the ×××HOLiC movie,
 * Umineko no Naku Koro ni plays with the trope; the party isn't specifically to kill the participants, but the more people that gather there, the less likely it is that someone important will die in the summoning of an ancient witch.
 * The opening chapter of Fairy Tail has a villain who uses magic to trick women into going to a party on his boat, then drugging them and selling them into slavery.
 * In One Piece, going to one of Big Mom's tea parties is usually a lot more pleasant than what she'll do to you if you refuse to go. However, during the Whole Cake Island Arc, where the party was supposed to cement an alliance between her and the Vinsmoke family, she was actually planning to assassinate them. The plan was foiled because Sanji (who was to be married to Pudding at the party  as part of the deal) overheard the plan beforehand. Of course, Vinsmoke Judge and Capone Bege were both planning - independently - to do so to her at the party; the good guys prevailed because the bad guys  were too concerned with each other.

Comics

 * In Hack Slash, Laura Lochs decides to wipe out a beach party full of kids on spring break as a protest against sexual permissiveness.
 * The massacre at the Bar With No Name during the original "Scourge of the Underworld" storyline, where eighteen villains were murdered, was a variation on this, except that the host wasn't behind it. The villains had met there to discuss the danger that Scourge posed, and because they knew at this point that he was a Master of Disguise, they doubled down on security, had everyone searched before entering, and they all checked their weapons at the door. Unfortunately, Scourge had disguised himself as the bartender, and no-one ever thought to search him, leaving them all vulnerable when he made his attack, gunning them all down.

Film

 * Goldfinger features the titular villain explaining his villainous plot, Project Grand Slam, to a group of foreign crime lords, just before releasing poisonous gas into the room. It's often wondered why he would have bothered, other than to provide an eavesdropping James Bond with the details.
 * Hey, gloating's fun. And at least he tried to kill all the witnesses afterwards. That's more than most villains remember to do.
 * Doesn't explain why he had that insanely elaborate room built, with the rotating furniture, the scale models... oh, right -- Bond movie. I forgot.
 * Several movies about The Mafia, like The Godfather and Some Like It Hot.
 * The movie version of Clue.
 * With the twist that one of the guests, and not the host, is doing the killing
 * I Still Know What You Did Last Summer has the villain Benjamin Willis concocting a convoluted plot to kill the heroine Julie and her friends;
 * In Hellraiser Hellworld
 * In The Final, a group of outcast students invite the bullies & snobs who have tormented them throughout high school to a costume party. It's not becuase they want to play Pin The Tail On The Donkey.
 * Inglourious Basterds features a Nasty Nazi Party where Shoshanna plans to kill the German high command by burning down her movie theater while they're in it.

Literature

 * Used in a book of The Dresden Files, in which the leader of Chicago's vampires invites everyone she hates to a party so she can kill them all.
 * Which is actually incredibly risky, because most supernatural entities operate under incredibly archaic rules of hospitality (like not killing someone you hate at a party), and the key thing about those rules is that if you break them they stop applying to you and it can be incredibly difficult to reverse that. Most supernatural beings follow these rules, if only because later on it may be the only thing that saves your sorry ass from a bad situation.
 * This is how the dictator gets rid of all his rivals on Gabriel Garcia Marquez's The Autumn of the Patriarch.
 * The climax of Victor Hugo's Lucrezia Borgia has the title character, a notorious poisoner, setting up one of these for the nobles who turned Gennaro, whom they did not recognize as her son, against her. Unfortunately, Gennaro is among the attendees at the party and tragedy quickly ensues.
 * The Bartimaeus Trilogy by Jonathan Stroud features more than one scheme of this type.
 * This was the plot of the R.L. Stine novel The Halloween Party.
 * The Red Wedding in A Song of Ice and Fire.
 * Done several times in Romance of the Three Kingdoms. Notable ones include Cai Mao's attempt on Liu Bei (unsuccessful), Zhuge Liang drugging a number of Nanman soldiers (they had been planning on using the banquet to make a surprise attack), and Zhou Yu's attempt on Liu Bei (also unsuccessful, as Liu Bei was accompanied by Guan Yu).
 * A strategy supposed to have been used by some Pictsie clans in Discworld. Always seems to fail because everybody gets too drunk to carry the plan out effectively.
 * Also referenced as a strategy in Interesting Times. However, Cohen points out it would not be appropriate to their situation, as they are up against 700,000 enemy soldiers. He also notes at great length that he would never use poison; his preferred method is to get everyone drunk and then cut their heads off.
 * Though one of Cohen's fellow octogenarian barbarians says they could still pull it off, if they did something easy for dinner, "like pasta".
 * The example above might be directly inspired by Conan. In one story, he starts a fight in the middle of a victory feast, wiping out the warriors of the tribe they were allied with but no longer need to. Apparently, this form of betrayal is a local tradition and thus not dishonorable (Conan's men were simply faster to act).
 * In the short story "Invitation to a Poisoning" by Peter Tremayne, the villain Nechtan invites all his enemies to dinner and then poisons  Inviting the heroine, who happens to be a professional investigator, to the party proves to be a mistake.
 * In John Christopher's post-apocalyptic young-adult novel The Prince In Waiting, the protagonist's father (ruler of the city where the action is set) is invited to a gathering and murdered.
 * Older Than Feudalism: Xenophon records at least two:
 * In one the Anabasis, the commanders of the army of ten thousand Greek mercenaries were invited to a banquet by their supposed Persian collaborator, Tissaphernes. He kills them, leaving the army leaderless (until a sneeze inspires them to elect new officers and march back to Greece).
 * In The Education of Cyrus, he indicates that Astyages (Cyrus' Mede maternal grandfather), attempting to seek revenge on his brother Harpagus, lured Harpagus' son to a banquet, killed him, and then fed Harpagus his son's flesh at the banquet. Then, in a truly inspired move, Astyages gave Harpagus command of an army sent to kill Cyrus. Instead, when they met, Harpagus joined forces with Cyrus to bring Astyages down. Rather a shocking move, wasn't it?
 * Mentioned in The Magician's Nephew by Jadis as how one of her ancestors dealt with supposedly rebellious nobles.

Live Action TV

 * Angel had a bachelor party where the groom and his family were planning to eat the bride's ex-husband's brains. (Long Story).
 * The new Doctor Who:
 * In "The End of the World", the villain attempts to create a hostage situation and position him/herself as one of the hostages. When that fails, he/she attempts to kill everyone in order to benefit from shares that he/she owned in their competitors. It is referred in this episode as "the Bad Wolf scenario" (which Silent Hunter thought about using as a title for this trope).
 * The episode "The Sound of Drums".
 * In Young Dracula, the Count invites his mortal neighbours to a 'Hunt Ball', with them not realising they are to become the prey for the vampire guests at the end of the night's festivities.
 * And the Carpathian Feast, where one vampire is roasted to death at the end of the evening. It's used by the Count to kill Erin.
 * The Avengers episode "The Superlative Seven" has the eponymous seven thinking they've been invited to a costume party. It's not.

Music

 * "I wore my black and white dress to the birthday massacre, birthday massacre, birthday, I wore my black and white dress..."
 * By the end of the song, said "black and white dress" has become a "black and red dress"...

Mythology

 * Towards the middle of the Nibelungenlied, Siegfried is murdered by his wife's brothers. The widow, Kriemhild, then marries the king of the Huns and invites her brothers and all their retinue to a feast. Unfortunately they've been forewarned, and turn up armed; the result is an all-night bloodbath only brought to a close when the Huns burn down their own hall. Oh, and according to some versions of the story this leads to a disgusted Hun taking out Kriemhild with a Diagonal Cut.

Tabletop Games

 * Pulled off simultaneously with a fake Heel Face Turn by Drachenfels, the Great Enchanter, in the backstory of Warhammer Fantasy Roleplay. He ostensibly repented his crimes, and publicly renounced evil, paid large reparations to his living victims, and abased himself at the graves of many others. He managed to gain the trust of Emperor Carolus and invited the whole imperial court for a feast at Castle Drachenfels. However, Drachenfels poisoned his guests, paralysing them. Helpless they saw how their children, which they had brought with them, were tortured. Afterwards they starved to death with a prepared feast before their eyes.

Theater

 * Once again The Zeroth Law of Trope Examples is invoked in Shakespeare's Titus Andronicus. A Nasty Party forms the climax of this exceptionally bloody early work.
 * The Movie does it beautiful justice. (at the end, you MUST yell "FATALITY!", trust me.
 * Nobody in Abigail's Party is trying to kill anybody, but it ends up being pretty nasty all the same.

Video Games

 * The Elder Scrolls III: Morrowind has a book that increases the player's Alchemy skill called "A Game At Dinner." Guess what the game is.
 * An assassin quest in The Elder Scrolls IV: Oblivion actually has you taking part in one of these. You get bonuses if no-one realizes you're the killer, and if you play your cards right you can actually get them to kill each other out of paranoia.
 * Mentioned in the bad ending of the first Laura Bow game.
 * This is why six of the seven murder victims are in the house in the mystery of The 7th Guest.
 * The "cake and party" at the end of the testing in Portal turns out to be
 * In Assassin's Creed II, Vieri de' Pazzi (Ezio's rival and later assassination target) is said to have served dinners "to die for" to entire families of those who beat him at contests.
 * In the first game, the assassination of "merchant king" Abu al-Nuqoub takes place at a party where he has poisoned the wine to kill all his guests.

Web Animation

 * Happens in the webtoon Big Bunny; in the story Big Bunny tells about the red, red, RED squirrel.

Web Comics

 * Sluggy Freelance has the "Displacement" Story Arc, where a Mad Scientist holds an auction for his Displacement Drive Vehicle. He's not actually interested in selling it; he just knows that anyone who wants to steal the Displacement Drive will try doing so at the auction. So, by killing everyone who shows up, he guarantees its safety! Too bad a lot of the bidders are also Mad Scientists and supervillains who don't take too kindly to this plan.

Western Animation

 * Kim Possible did this twice, both times at Camp Wannaweep, and both times, it was Ron's archenemy Gill who wanted to kill and/or mutate them.
 * Also Dr Drakken has twice invited groups of famous scientists to conferences/traps. The first time, he invited Kim's father, a former schoolmate, without connecting the surname "Possible" to his nemesis ("It's a common name! Who knew?"). The second time he intentionally omitted Dr. Possible from the invite list to avoid attracting Kim's attention (it didn't matter, Kim was visiting her uncle at the Possible Ranch right down the road).
 * The Venture Brothers had an episode where Dr. Venture, Brock, Baron Ünderbheit and Pete White all attend the funeral of a friend from college, only for the friend, who wasn't really dead, to kidnap them all in revenge for their wronging him. It turns out that these slights all had to do with the man's crush on a girl at college; the four "victims" all mock this since the girl never knew he existed in the first place and the whole crush bordered on stalkerish obsession. Then it turns out the friend had died, ages ago, and the scheme was being carried out by a robot duplicate.
 * There was also the episode that introduced Underbheit where he holds a meeting with his subordinates and subsequently attempts to kill them. A later episode shows he failed, two of them run a resistance against him, a third is being held captive in his bedroom.
 * The Futurama episode "Crimes of the Hot" culminates in this sort of gathering, orchestrated by president Nixon's head.
 * The Space Ghost Coast to Coast episode "Surprise" has Moltar and Zorak rounding up the Council of Doom so they can throw a surprise party for Space Ghost's birthday. And by "surprise party", we mean "ambush". After suffering through a host of painful distractions, Space Ghost comes back, sees through their transparent attempt at hiding behind a curtain, and blows them up with his power bands.
 * Subverted in "The Creeps" episode of Adventure Time. The protagonists are invited to a dark, spooky castle (which is heavily lampshaded), locked in, and then receive a message that a ghost will possess one of them and kill the others. This appears to happen, but eventually turns out to be a prank by Jake targeting Finn. Double subverted (?) since Finn intended to prank Jake and staged the first two "murders" accordingly; Jake found out about Finn's plans well in advance and turned the tables on him.
 * In the Rick and Morty episode with Tammy and Bird-Person's wedding, Tammy (who is secretly an agent of  the Federation) actually uses the reception as a sting operation  in an attempt to arrest the main cast.

Truth in Television

 * Niccolo Machiavelli, in his classic work of political science The Prince, describes just such a banquet hosted by Oliverotto Da Fermo. Oliverotto invited all the nobles of Fermo who might oppose him to a banquet, then invited them to meet with him privately to discuss serious political matters—in a room where he had armed men waiting to massacre them.
 * Not to mention the legendary original "Night of the Long Knives" in early British history, when in around 460 AD the Saxons allegedly massacred the British nobility at a banquet to celebrate a peace treaty, reducing King Vortigern to their puppet.
 * Vlad the Impaler supposedly did this a couple times, once reacting to a begging epidemic in one of his domains by inviting all of the beggars to a huge Christmas party, locking them in, then setting the place on fire.
 * There was also the time, early in his first reign, when he invited nearly all of Wallachia's ruling nobles to a fancy Easter feast. During the feast he asked them, almost idly, "How many rulers of our nation have you known?" The nobles responded that they'd all known anything from half a dozen (for the youngest) to more than they could remember, all of them taken down by their own backstabbing and conniving. One of these nobles had been Vlad's own father. The enraged Vlad called in his troops, told them that they were ruining the nation by their treachery, and worked them and their families to death building a new castle for him. He promised that the survivors would be "Raised above all other men." And they were... He had them impaled.
 * This has happened so many times in Islamic history:
 * The first time was when the Abbasid dynasty, Abu al-Abbas Saffah, invited 80 princes of the previous Ummayyad dynasty to a banquet and had them all stabbed. His men then covered the bodies with rugs and then the actual banquet, with other guests, commenced. To this day, "saffah" is the Arabic word for "Serial Killer".
 * Another time was in 1811, when Muhammad Ali Pasha, the Ottoman governor of Egypt (although "governor" is hardly the right word, since by that time he was de facto independent of the Sultan in Istanbul), lured the leaders of the Mamluk ruling class to a banquet in his citadel. He had them go down a dead end, trapped them, and had them all shot.
 * The story known in Toledo, Spain as La Jornada del Foso ("The Day of the Ditch"). In early Muslim Spain, the former Visigothic capital at Toledo often went its own way and paid little attention to the emir sitting in Cordoba. Thus, one day around the year 800 AD, the emir sent a new governor named Amrus to Toledo who invited the most influential nobles of the city for a party to his palace, and placed a pair of executioners armed with axes behind its entry gates. Thus, each time a "guest" crossed the door, the executioners cut his head off and threw the body in the titular ditch. From then on, Toledo remained calm and in a tight leash - until 30 years later, when Amrus died and coincidentally, the sons of the executed found themselves to be old enough to rebel against Cordoba.
 * In 1929, gangster Al Capone learned that three men intended to betray him. He invited them to a lavish banquet, and once they'd eaten and drunk their fill ordered his bodyguards to tie the men to their chairs. Capone worked all three over with a baseball bat, before finally ordering his guards to shoot the would-be betrayers and dump the remains.
 * Jim "Shanghai" Kelly, one of the most notorious crimps (maritime kidnappers) in the 19th century, was said to have once thrown a "birthday party" for himself in order to attract enough victims to man a notorious sailing ship called the Reefer as well as two other ships.