Hoist by His Own Petard/Film

"Hannibal: Hey, Cordell. Why don't you push him in? You can always say it was me."
 * In Trading Places the Duke Brothers' are the architects of their own demise. The two "guinea pigs" they choose for their 'experiment' wind up figuring out what's happening and hatching their own plot. The same former guinea pigs use the Dukes' own orange juice market plot against them. Even the hooker they got to help ruin Winthorpe's life and the butler they drafted into their plan wind up playing small roles in bringing them down. Geez, they'd have gotten off easier by just being honest businessmen.
 * In any given Marx Brothers film any dialogue between the two resident Pungeon Masters was likely to end with the quick-witted Chico getting the better of the exasperated Groucho by turning his own wordplay against him.
 * Aliens: the Corrupt Corporate Executive who ordered the colony to acquire the alien eggs (and thereby caused all of their deaths) was eventually killed by the aliens himself.
 * The film Merlin has Mab. She created Merlin (half-human, half-fae) to preserve the old ways. But, her cruel actions such as killing his mother and imprisoning a lady he loved, made him instead want to destroy the old ways. When he succeeds, Mab literally disappears because Gods Need Prayer Badly.
 * Sweeney Todd: The Demon Barber of Fleet Street ends with the cannibal butcher Ms. Lovett being shoved into her own oven. Todd has his throat slit with his own razor, exactly as he did to his victims.
 * The unspoken reason for Rotti Largo's terminal illness? Exposure to the same poison that he used to kill Marnie Wallace.
 * Vic Deakin (played by John Travolta) of John Woo's Broken Arrow 1996 hilariously and literally gets hit by the nuke he intended to slaughter innocent millions with. It doesn't detonate, though.
 * In Dumb and Dumber, an enemy poses as a friendly hitchhiker, intending to drop pellets of rat poison into Harry and Lloyd's food. But before he can succeed in this, he needs first aid when his ulcer flairs up (which was induced by Harry and Lloyd's own practical joking). Harry and Lloyd try to administer his emergency pills, but they mistake the pellets of poison for the ulcer medication, and feed him his own rat poison instead.
 * In Stealth, a medic attempts to inject an initially unsuspecting Ben (Josh Lucas) with 'pain relief' medicine (actually poison). Ben politely refuses, but the medic's stubborn insistence clues Ben in that something is wrong and a struggle ensues. The medic ends up being stuck with the needle himself and dies, showing Ben what the medic was trying to do (not that it wasn't fairly obvious).
 * This moment in itself leads into Ben's commander being hoisted by his own petard. In trying to cover his tracks by having Ben killed and failing, his duplicity is revealed to his superiors by Ben and he is relieved of command. Then he takes a bullet rather than face court martial.
 * In Who Framed Roger Rabbit, after Judge Doom reveals himself to be a toon, he meets his end by getting sprayed with "Dip," a toon-killing cocktail of paint thinners that he himself created.
 * In Dream House,  tries to kill Will and   in a house fire. It does not end well for him.
 * General fate of James Bond's adversaries. Some examples: Doctor No's metal hands made it impossible for him to climb to safety (admittedly, he would have even more of a hard time without any hands at all. On the other hand, he lost his hands from his work with nuclear reactors in the first place), Oddjob was electrocuted through his steel-bladed hat, Goldfinger was sucked out of his own depressurizing jet, Trevelyan was crushed by his own evil satellite dish, Carver got shredded by his own giant drill, Renard was skewered by a rod of plutonium with which he was trying to blow up a submarine, Baron Samedi is knocked into the casket full of poisonous snakes into which he was intending to sacrifice Solitaire, etc.
 * If The Dragon in a James Bond film is not killed by being Hoist By His Own Petard, chances are he's not really dead...
 * In Moonraker, James Bond kills a knife-throwing assassin by throwing one of the knives back at him.
 * Hellboy: Kroenen dies in his own spike pit.
 * Don't forget Hellboy crushed him with his own giant gear.
 * In Golden Army, Mr.Wink dies after launching his Rocket Punch into a griding machine. Hellboy even states before "I wouldn't do that" and after that happened "Whoa. Told ya."
 * Nearly occurs in Iron Man, where the shrapnel that forces Tony Stark to wear his electromagnet comes from a Stark Industries missile used by terrorists. Obadiah Stane's Iron Monger suit was also reverse-engineered from the remains of Tony's first suit.
 * Not to mention Stane being killed by the same device he decried as useful only for "publicity."
 * In the sequel, lots of Hammeroids get blasted out of the air by fire from their own. Also defied, according to the novelisation, as Ivan Vanko specifically constructs his armour so that in case of a mishap (which incidentally doesn't happen) he won't cut himself with his whips.
 * In Super Mario Bros, Mario and Luigi use Koopa's own de-evolution guns against him, turning him into a tyrannosaurus. Then they blast him a second time, turning him into primeval slime.
 * Tank Girl. Kesslee had a device that drained a person's blood from their body, killing them, and purified it into drinkable water. He used it to kill one of his subordinates, and at the end Tank Girl used one to kill him.
 * Doc Savage: The Man of Bronze. The Indian who had acted as Captain Seas' assassin by using the Green Death (created from the venom of poisonous snakes) falls into the pit holding the snakes and is bitten repeatedly, killing him.
 * At the climax of GMK, Godzilla explodes after his own nuclear breath backfires and instead tears him open from the inside out. Somewhat a subverted example in that, Godzilla isn't killed but instead reduced to a disembodied yet still-beating heart.
 * In Hannibal, Mason Verger is eaten by the killer pigs he had been training to eat Hannibal Lecter. There's even a bit of The Dog Bites Back added in for good measure.

"Bridgekeeper: What is the airspeed velocity of an unladen swallow?
 * The bridgekeeper in Monty Python and The Holy Grail:

King Arthur: What do you mean? African or European?

Bridgekeeper: I don't know that! AAAAAAGGHHHH!!!!"


 * In Help I'm a Fish, Joe the pilot fish dies (rather horribly) when he drinks too much of the Anti-Fish potion, effectively turning into a human. Whilst underwater. He drowns.
 * The Avengers 1998. While Sir August is fighting Steed, he's stabbed through the chest with his own fighting staff and then hit by a bolt of lightning from his Weather Control Machine and killed.
 * In The Pink Panther Strikes Again, Former Chief Inspector Dreyfus is killed when his Bavarian castle is disintegrated by his own doomsday weapon. It was supposed to be fired at England, but Clouseau hoist himself into the castle with a conveniently placed catapult. He proceeds to land on the doomsday machine, causing it to swivel around and hit Dreyfus instead, who has his legs disintegrated. Then the doomsday device overloads and starts to dissolve the rest of the castle. The last thing we see of Dreyfus is him slowly vanishing while playing the organ that any self-respecting villain must have in his Bavarian castle hideout.
 * Dreyfus comes back in time for Revenge of The Pink Panther.
 * In Perfume, Grenouille ends his own life by dumping his perfect perfume over his head, causing a nearby crowd to become overwhelmed by the concentrated beauty and devour him.
 * In the first Transformers live action movie, the Decepticon Frenzy is killed by one of many CD like 'throwing stars' which he himself fired. The thing arced in mid-air and came right back at him.
 * Starscream's Chronic Backstabbing Disorder comes back to bite him in his shiny, metal ass terminally this time in Transformers the Movie when he dumps the badly damaged Megatron out into space. This of course, puts Megatron in a position to be found by Unicron and reformatted into Galvatron. Naturally, Galvatron decides to test his new weapons out on Starscream.
 * In Spider-Man, The Green Goblin is stabbed in the chest by his own glider after trying to use it to kill Spider-Man (Spider-Man senses it, and quickly gets out of the way). This led the Goblin's son to believe Spider-Man killed his father.
 * In Bride of the Monster, Dr. Eric Vornoff is killed by his own giant octopus. "He tampered in God's domain."
 * Ghost Rider's Penance Stare allows him to burn the pain of all the people someone has hurt into that person's soul. The film's villain, a demon, has no soul and is thus immune. Near the end, he takes on the power of 1000 evil human souls to start the apocalypse. Guess what happens.
 * Jurassic Park uses this; create prehistoric monsters and there is a good chance they'll kill you. It is played better in the book and the dinosaurs aren't created as weapons but for entertainment but it otherwise fits the trope.
 * Rather literal in Law Abiding Citizen. Clyde is about to activate the bomb he set up in city hall. Nick tries to talk him out of it. He activates it anyway, and Nick leaves him in his cell and locks the door as Clyde realizes the bomb is now in the cell with him. He accepts having finally been outplayed and sits on the bomb as it goes off.
 * The Wind in The Willows/Mr. Toad's Wild Ride: Chief Weasel tries to blow up Toad Hall from the dog food factory. Rat switched the labels on some barrels labeled "bones" and "explosives" earlier on. You can probably figure out how this ends...
 * In Disney Animated Canon's Tarzan, Clayton repeatedly tries to slash Tarzan with his machete. Unfortunately for Clayton, the two of them are fighting in a thick jungle, where Clayton cuts just the right vines to accidentally hang himself.
 * In Godzilla Final Wars, Gigan fires two spinning disks from his chest at Mothra, who dodges it. Gigan then sets Mothra ablaze with his laser beam. As Mothra is burning, Gigan turns around to savor his victory, only to have the two spinning disks come back and decapitate him.
 * It is not really known why the disks came back, although the yellow powder Mothra threw might've been the cause, as Mothra has reflective scales in the films Godzilla vs. Mothra and Godzilla: Toyko SOS.
 * In Edge of Darkness 2010, Craven gains a measure of symbolic revenge when he forces Bennett, the man who ordered the radioactive thallium poisoning of both Craven and his daughter Elle, to drink a jar filled with thallium-tainted milk.
 * In Traitor, the Deep Cover Agent protagonist Samir is unable to break his cover by giving the suicide bombers that are planning to blow up busses in the United States fake equipment. His solution? He arranged for them all to be on the same bus, so that they only managed to blow each other up.
 * Kinda sucks for the bus driver, though.
 * In Resident Evil Afterlife, Albert Wesker escapes from the ship in a helicopter, then triggers the ship's self-destruct device, only to find that Alice found the bomb earlier and stashed it on the helicopter.
 * In Crouching Tiger Hidden Dragon Jade Fox tries to kill Mu Bai with a hail of poison darts, but Mu Bai deflected them back at Jade Fox.
 * A literal example of this trope occurs in The Lord of the Rings: The Two Towers, where the torch-bearing orc clearly didn't make it out of the explosion place. Also many orcs were crushed by flying boulders, not that this stopped the others much.
 * The director's cut also gives us a straight example: the dam that Ents break to flood Isengard was recently constructed by Saruman to speed up weapon production. It was also said production that made felling that many trees necessary, giving the Ents a reason to attack in the first place.
 * Flash Gordon. At the end Ming is impaled on the nose cone of one of his own war rockets.
 * "Dick, you're FIRED!"
 * In the sequel, Faxx shuts off Cain's life support and uses his brain to create Robocop 2. Later, Cain goes on a rampage when OCP unveils him, and Faxx becomes OCP's scapegoat. Cain himself is defeated when Lewis offers him a canister of his own drug Nuke, and Robocop takes advantage of the distraction to kill Cain.
 * The Terminator series is a prime example of this trope. We created the Skynet system, and right after it comes online it tries to eradicate us by implementing an all out nuclear war.
 * Batman Returns has the Penguin getting this in spades. When he appears to have the race for Mayor of Gotham City in the bag, Bruce Wayne and Alfred broadcast his previous rants directed at Batman over the loudspeakers during his speech, which include such gems as "I played this stinking city like a harp from hell!" Penguin's Villain With Good Publicity status goes bye-bye, and the eggs and tomatoes are broken out. Later, after his plot to kill all the first-born sons of Gotham is foiled, Penguin straps rockets to his hundreds (thousands?) of penguins in order to destroy the city. Alfred is able to jam the signal used to control them, sending them off to follow a new beacon. When Batman arrives at his Elaborate Underground Base, Penguin wields a sword-umbrella, only for Batman to simply pull out a small remote control with a blinking red button. His eyes shift from the control, to something on the opposite side of the screen. Penguin does likewise, and sees his entire penguin army. He snaps (further than he already had) and is able to take the controller and press the button. The rockets launch, destroying what remains of the park, but also releasing a swarm of bats from the Batski which immediately descend upon the Penguin (a double Hoist By His Own Petard when you remember that he used a similar swarm of bats released by an umbrella in order to send the Ice Princess off a building and kill her, framing Batman for the whole thing). He stumbles backwards, through the ceiling glass, and into the icy polluted water.
 * Max Shreck, the other major villain, after receiving a Humiliation Conga of his own for his manipulation and betrayal of the above villain, is eventually electrocuted by a power overload to the Arctic World park (presumably coming from the power plant that he had been doing a lot of his evil doings for), with the Kiss of Death delivered by none other than Catwoman, whose alter ego (Selina Kyle) he had been treating like shit through most of the movie. Turns out that one really can have too much power.
 * In The Pelican Brief, a hitman who had previously planted a car bomb rigs another car in a second attempt to kill the heroine. Luckily, when the car has engine trouble, she recognizes the sound from the previous incident and gets out of the car to flee. The villain attempts to run her down in his own car, but loses control and crashes. Ironically, the impact alone would probably have been enough to kill him, but the car he crashed into? The very one that he rigged to explode. KABOOM.
 * Towards the end of Popeye, Bluto, who is already winning the fight against Popeye, decides to rub it in by shoving spinach down Popeye's throat . Of course, the spinach gives Popeye the strength to win the fight.
 * In the climax of Strange Days, protagonist Lenny Nero, after literally getting stabbed in the back by his former best friend Max, ends up clinging for dear life to balcony railing twenty-two stories above the streets of Los Angeles, with Max dangling from his necktie hoping to take Lenny down with him. Lenny proceeds to pull the still-stuck knife out of his back and use it to cut his tie off, sending Max plummeting to his death.
 * Bo Catlett imagines how easy it would be to kill Chili if he just had Bear loosen some of the screws on the railing of his deck, which overlooked a cliff. When the eventual showdown happens at Cat's place, he's surprised to learn Bear actually did loosen them.
 * Subverted in L Change the World, in that K is perfectly willing to die from the virus she created so long as it achieves her goal of ridding the world of humanity..
 * Non-Fatal version appears in Daredevil, when Matt Murdock's partner Foggy puts some stuff in Matt's coffee as a practical joke. The moment Foggy's head is turned, looking at Elektra, Matt switches their coffees, giving Foggy a taste of his own medicine.
 * At the end of Dirty Pretty Things, the villain, who runs an illegal organ harvesting operation that preys on desperate illegal immigrants, has the tables turned on him by the heroes, who knock him out and steal his kidney.
 * Pirates of the Caribbean: In At World's End, Barbossa not only cites the code at the gathering of the Brethren Court, but calls on Captain Teague to enforce it, all to avoid fighting Beckett. Jack's motion for the Court to fight won't be entertained because only the elected Pirate King can declare war, and there's no King because a Pirate Lord will always only vote for himself. So Jack calls for an election, lets everyone else vote for themselves, then throws his support behind Elisabeth, who's gung-ho for bringing war on Beckett. Now Barbossa has to go to fight Beckett, since he not only cited the rule that says Elizabeth can declare war, but called on Teague as well. He's got a better chance of surviving a war than a fight with Teague.
 * Lord Shen in Kung Fu Panda 2 invents cannons, which he uses to kill some of the best kung fu masters in China and plans to conquer all of the land. Po manages to find inner peace and masters the technique for catching raindrops without breaking them, which he uses to catch cannonballs and throw them back. Thus Shen's entire armada gets destroyed by their own weapons. He is killed when he tries to kill Po with his knives and accidentally cuts a rope that holds his biggest cannon, which falls on him.
 * At the end of Robots, Big Bad Madame Gasket falls into her own incinerator, which she was previously established as using to melt down lower-class robots into products for her son's company to sell.
 * In the original 1960's Oceans 11, Danny Ocean's team decides to hide the stolen cash in 's coffin. The plan was to wait until it was shipped to San Francisco for the funeral and buried, after which they would retrieve the money. This went quite wrong when his widow, who had not been informed of this, decides to have the funeral there in Las Vegas... and the money then gets burned with him.
 * Inglourious Basterds: The Nazis were trapped in a theater and burned - gunned down if they tried to escape - just like they had done to Jews in synagogues.
 * In Muppet Treasure Island, the first step of Silver's planned mutiny is convincing First Mate Mr Arrow to leave the ship in a leaky lifeboat, causing the rest of the crew to assume he drowned. When the plan fails and Silver winds up in the brig, he escapes and flees the ship... in a lifeboat which later turns out to be incredibly leaky.
 * Weekend At Bernies starts this way: Bernie defrauds his own insurance company and rewards the two employees that discovered it with a weekend retreat at his place. He intends for the mob to off them; the mob offs him instead. Hilarity Ensues!
 * Harry Potter Part 2 has one involving Snape. He invented Sectumsempra, a spell used for emulating the effect of a sword. Guess exactly which throat Voldemort slices with it? (In the book, Nagini is used instead.)
 * At the end of Snow White and The Seven Dwarfs, the Evil Queen (disguised as the Witch) actually threatens to kill the seven dwarfs by crushing them with a boulder after they've discovered that she actually "killed" Snow White with a poisoned apple and had her cornered at a cliff. Just right before she dislodges the boulder, the Queen is immediately hit by lightning, and tumbles off the edge. Shortly afterwards, her own boulder falls off the same cliff in the same direction as the Queen.
 * In Hunchback of Notre Dame Frollo, while trying to kill the heroes, keeps hacking the stone gargoyles they are clinging to with a sword. The circumctances conspire so that he has to use one of the gargoyles for support, but the cleaved stone breaks under his weight and he plunges to his death.