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Knockout Gas

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Sweet dreams, Vicky.
Dr. Carmichael: And the guards, how will you manage them?
Root: I won't have to. They'll be incapacitated from the desflurane in the ventilation system. It vaporizes at 75 degrees, which the building climate control has been programmed to reach ten minutes ago.

In fiction, one of the easiest ways to incapacitate an opponent or group of opponents is to get them in a closed room and pump in Knockout Gas. Some forms of Knockout Gas are an area-effect form of Instant Sedation: as soon as the victims breathe it, they cough weakly a few times and then slump to the floor unconscious. Other forms give the victim enough time to lay down comfortably before falling asleep.

Usually delivered as a visible fog, and often brightly colored as well, but invisible gas is also common, particularly in budget-conscious productions. Knockout Gas can be delivered through special vents just for that purpose, or it can be pumped in through the regular ventilation system. As with other forms of sedation, dosage doesn't seem to matter. The effects last just long enough for maximum tension or drama. Recovery tends to be just as fast as the onset, and the victims rarely suffer any lasting effects beyond, perhaps, a mild headache. Nobody ever seems to crack their skull or otherwise get hurt when falling down, either.

Frequently employed by villains, but also a convenient weapon for heroes due to its non-lethal nature.

Often involves Instant Sedation, and related to One Dose Fits All. Sister Trope to Deadly Gas (and in Real Life, though almost never in fiction, the line between the two can be a very fine one.) Sister Trope to Laughing Gas. Sister Trope to Tranquillizer Dart. Hand Sliding Down the Glass is a subtrope. Often used in a Knockout Ambush. Often results in Non Sequitur, *Thud*.

Though anesthetic and hypnotic gasses of many sorts exist, and are still occasionally used in veterinary medicine,note  all have the properties of being fairly slow-acting, decidedly dosage-dependent, and fairly easily lethal, unlike the gasses in this trope. Therefore, please refrain from citing real life examples.


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    Anime & Manga 
  • Dieci in Magical Girl Lyrical Nanoha StrikerS has the Aerosol Shell of her Enormous Cannon, which releases fast-acting knockout gas after they explode on impact as shown during the assault on the Ground Forces HQ. Unlike the more colorful gases used in many other media, these have the appearance of ordinary white smoke.
  • In the Cowboy Bebop episode "Waltz for Venus", during a hijacking, Faye renders a female hijacker unconscious with a spray of vapor.
  • Used a lot by Genzo, with the gas usually stored in his puppets.
  • In One Piece, half of the Straw Hats fall victim to this whilst the others are exploring Punk Hazard. The Arc Villain Caesar Clown also uses a variation of the trope. He doesn't knock out people with gas, but rather lack of gas: he uses his powers to take away all of the oxygen from a specific area, and thus suffocates the opponent to unconsciousness.
  • One of Kaito Kid's tricks in Magic Kaito, as seen used in the OVA.
  • In Dragon Ball when Goku and friends are captured by Emperor Pilaf he floods their prison with sleeping gas to knock them out so he can search for the remaining dragon ball they have while they're all unconscious and can't do anything. He then enters the chamber before the gas has begun clearing out and knocks himself out too.
  • In Brave10, a special Iga knock out gas is used during Goemon's attack on Ueda castle. Unfortunately for the Ishikawa gang, all the Ninja Braves have Acquired Poison Immunity. Although the attack is relatively serious, it's Played for Laughs the morning after for those who were out, with Isanami wondering whether she crossed the line with Saizo the night before and just can't remember, and Yukimura waking up to discover the heavy weight he feels is Rokuro lying on top of him.
  • Snow White with the Red Hair: One of Touka's concoctions functions this way when tossed onto a fire, he has a version of it that is altered to be more deadly as well though it is possible this is the same concoction in different amounts since the "antidote" that prevents one from passing out dead asleep from the first version still works with it, it just does not prevent the victim from becoming ill and dying. It also takes a bit longer to put those inhaling it to sleep than most examples.
  • Attack on Titan features a take on this trope that's halfway between this and Deadly Gas. It's revealed that this is how the residents of Connie's village Rakago got turned into titans. Zeke, who has royal blood, can control titans created with his serum. In the case of Rakago, it was an experiment to see if gas containing Zeke's serum could also turn Eldians into titans. Essentially, Connie's entire village got gassed and subsequently were forcefully transformed into titans.

    Comic Books 
  • The Incredible Hulk: One of the most consistent ways of defeating the Hulk, at least on those occasions when he doesn't remember that he can hold his breath for hours. As the Hulk isn't all that bright, this is not infrequent. However, if he gets too angry his metabolism will dispel it completely.
  • Hawkeye uses trick arrows, one of which, is a knock-out gas arrow.
  • Batman has used knockout gas from various sources: bombs, canisters, guns, etc.
  • As with the movie and TV versions, the comic versions of The Green Hornet have also used knockout gas.
  • Enemies of Spider-Man have used it from time to time. Mysterio, Kraven, the Chameleon, the Hobgoblins, and Green Goblins are all culprits.
  • DC Comics' golden age hero Sandman, one of the members of the Justice Society of America, used a knockout gas gun. Later versions of the character also used knockout gas.
  • In Amazing Spider-Man #661, Veil turns into isoflurane, an anesthetic gas, to keep two muggers down. True to the usual depiction, despite the gas generally being colorless, it appears as a thick fog.
  • In Jet Dream, Jet uses "Kayo Powder" in a makeup compact for this effect.
  • In Tintin - Tintin in America, the Gangsters Syndicate of Chicago uses knockout gas on Tintin after dropping him through a Trap Door and before dumping him into Lake Michigan. Fortunately for Tintin, they used the wrong kind of gas.
  • In American Flagg!, Somnabutol™, in low doses, is a recreational drug. In higher doses, it's "the Official Riot Control Device of the 1996 East Coast Meltdown." Also described as "like a wet dream without the hot parts."
  • In The Uncanny X-Men, in one issue, Cyclops is being chased by the rest of the X-Men who have been tricked by Mastermind into thinking he's Dark Phoenix come back to life. He lures the X-Men into the Danger Room, where he uses a field of "Wizard of Oz" poppies keyed specifically to knock Rogue unconscious. He does this so that he can use her power absorption power to take brief control of a comatose Professor X's psionics to pierce Mastermind's illusion.
  • Wonder Woman:
    • Wonder Woman (1942): The Saturnian Count Mephisto Saturno floods Washington DC with Lassitude Gas, which is colorless and odorless and makes people feel listless and then fall asleep.
    • Wonder Woman (1987): The Sangtee Empire pumps knockout gas into disabled ships found during their patrols before boarding and stealing them and enslaving any outsiders on board.

    Fan Works 
  • Calvin & Hobbes: The Series:
    • Used by Evil Jack on Calvin and Hobbes in "62 Percent More Evil". It comes in a deodorant can.
    "Designed to render unconscious and keep you smelling like pine for at least two hours."
    • Sherman later uses it on Andy's parents in "Dark Laughter".
  • Lavandula Somnambulist: Much like his mother, Izuku's quirk allows him to emit gas that can knock people unconscious. Here, it comes from his mouth, and can even make the unconscious bodies do his bidding to a limited capacity (making it fit the name "Somnambulist" more so than his mother). While he has fairly good control over it, he can suffer Power Incontinence when he gets excited so he wears a face-mask when out in public.
  • The Rigel Black Chronicles: Harry encounters a non-lethal nerve gas during the free-dueling tournament. Her opponent compliments her on forcing him to use it; he'd planned to save it for a later fight. She nearly manages to flush it out of her system, too, but he takes advantage of her distraction to end the fight.
  • With This Ring: Once he gets access to a proper technology database, the protagonist is able to manufacture a variety of gases for use on different alien species. Thanagarian riot gas seems to be the one he's had to use most often.

    Films — Animation 
  • Injustice (2021). Green Arrow has captured Harley Quinn with a net arrow. When she keeps yacking away, he takes out another arrow and hands it to her.
    Quinn: What does this one do? (arrow sprays green gas in her face) You suuuuuuuck.... (collapses)
  • The short film Interstella 5555 that goes with the Daft Punk album Discovery starts off with an entire stadium full of concert-goers subdued by black-suited mooks with devices that shoot pink gas. The entire stadium goes down in seconds. The one person who escapes is taken down with a specialized crossbow bolt whose head bursts into a similar cloud of pink smoke.
  • In Cars 2 sleeping gas is sprayed on Mater after he is put inside a truck.
  • Justice League: Crisis on Two Earths. Batman is getting beaten up by Superwoman, so he throws out some bomblets which spray green gas everywhere. Superwoman just inhales the lot and mocks him for attempting a Smoke Out.
    Batman: (wearing gasmask) It's not smoke. (Superwoman starts coughing) It's anesthetic gas. (Superwoman passes out)
    • Later Batman tries spraying gas in the face of his Evil Counterpart Owlman, who just grins and drops the transparent faceshield on his Powered Armor.
  • Megamind's Minion possesses a Knockout Aerosol can, which he mostly uses on Roxanne in her endless kidnappings. Halfway through the film he runs out of it and resorts to Forget-Me-Stick.
  • The Simpsons Movie: Bart, Lisa and Marge are put to sleep with knockout gas.

    Films — Live-Action 
  • In The Film of the Series of The Avengers (1998) Father knocks Mrs. Peel out instantly with gas from an aerosol can.
  • In 1966's Batman: The Movie, Batman and the Penguin each use a gas that causes instant unconsciousness (called Bat-Gas and Penguin Gas, respectively).
  • Cats & Dogs. To capture the Brodys, the evil cats send fake tickets to a soccer game to them, then when the family pulls up in their car, the cats throw in a knock-out gas bomb leaving the family unconscious to take hostage.
  • The 1933 German film FP1 has the eponymous City on the Water sabotaged by gas pumped through the sprinkler system. One everyone's unconscious, the flood valves are opened and it's left to sink. Fortunately our heroes land an aircraft on F.P.1, then smash all the windows to let the gas out and wake everyone up.
  • James Bond
    • Diamonds Are Forever. While James Bond is in Willard Whyte's elevator, Blofeld renders him unconscious with knockout gas.
    • The Spy Who Loved Me: Anya Amasova uses a trick cigarette to blow knockout gas into Bond's face.
    • Averted in GoldenEye where it looks like James is using a sleeping gas canister to block the entrance to the room, but it turns out to be a grenade.
  • Britt's iconic Gas Gun is included in 2011 The Green Hornet. It instantly puts anyone to sleep for about an hour, though this was only after Kato experimented with and perfected it. Britt was accidentally exposed to the first mixture, which put him out for eleven days.
    Britt: I was out for eleven days?! I wasn't asleep, that was a coma, you dick! Did you put this diaper on me?!
  • In Help!, a sinister red gas takes out all of the Buckingham Palace guards in a matter of seconds.
    Ringo: It must be their tea break.
  • In The Hunger Games: Mockingjay Part 1, the rebel team sent to rescue the Victors uses sleeping gas bombs to clear areas before they enter. Peeta gets knocked out by the gas as well, and comes to in the hospital at District 13.
  • Lou. The kidnapper removes the doorknob and inserts a tube that sprays halothane into the child's bedroom.
  • Mystery Men has Captain Amazing fall victim to Casanova Frankenstein's fiendishly clever Chloroform-Deploying Enticement Snare.
  • Operation Fortune: Ruse de Guerre: When he breaks into the Ukrainian's villa, Orson connects a tank of knockout gas to the air conditioning system and floods the place with gas until everyone falls asleep.
  • Even the great El Santo proves vulnerable to a knockout gas grenade thrown by a hunchback in Santo y Blue Demon contra Drácula y el Hombre Lobo.
  • Strange Psychokinetic Strategy had yellow smoke knocking out half a dozen police, from a cymbal-smashing monkey.
  • Thoroughly Modern Millie: The antagonist is pumping a white sleeping gas into the room of someone she plans to kidnap and sell into slavery, the problem is that she is in the room with the gas. As the gas gets thicker in the room she starts to yawn, slows down, and finally just falls over onto the bed; the gas has dissipated by the time she is found, still asleep.
  • Artemus Gordon's sleeping gas billiard balls in Wild Wild West. The logic of having sleeping gas disguised as a billiard ball is lampshaded by Jim.
    West: Well I don't know about you, but I'm certainly gonna sleep better, assuming Loveless barges in here and wants to play a game of pool.
    • Except for the 8-ball, which is an incendiary bomb.
  • In Close Encounters of the Third Kind, the Army douses the Devil's Tower mountain with sleeping gas to prevent any unevacuated civilians from setting eyes on the UFO landing zone. Jillian and Roy manage to escape it, but Larry succumbs.
  • In Old, Dark House horror comedy The Monster, the room that Johnny, Amos, and Betty are in has a fireplace that starts emitting knockout gas. Johnny and Amos escape, but Betty is captured when the bed she's lying on turns out to be a trap that's lowered into the basement.
  • Ethan suffers from this after receiving a taunting briefing from the Syndicate in Mission: Impossible — Rogue Nation, but not before witnessing Solomon Lane executing a shop girl. Later, Ethan does almost the exact same thing to Lane, and then arrests him.
  • The Gas of Peace in Things to Come, except for the warlord who fails to realize the benefits of One World Order and conveniently dies of a heart attack after inhaling it.
  • As with most spy movie tropes, shows up in Get Smart.
    Max Knockout gas, Agent 99? Please. I have trained my body to be impervious to- *eyes roll back in his head* oooh that's new stuff. *falls over*
  • The gang throw a knockout gas grenade into the security car trailing the armored van during the Armed Blag on the Tower Bridge in Circus of Fear.
  • In King Kong (2005) the boat crew knock Kong out by chucking large bottles of chloroform at him.
  • King Cobra (1999): The film ends on a Wham Shot as it's revealed that the giant cobra was merely inoculated, as the gas canister used against him was the wrong one, and only contained sleeping gas.

  • Lone Wolf features knockout gas in Castle Death, filling some trapped rooms or delivered by an ugly dwarf blowing it in your face through a brass tube.

  • Doc Savage used anesthetic gas grenades. Somewhat justified in that Doc was supposed to have specifically invented these.
    • In Fear Cay, one of the Doc Savage novels, the bad guys try to capture Doc with Knockout Gas dispensed from a rigged wallet left on the sidewalk where he would find it. It doesn't work, because of his superior ability to smell (he somehow smelled it before he breathed it) and (as with the Hulk) his ability to hold his breath for much longer than normal. In this case it was not visible.
  • In the eighth book of the Dog Man series, Grampa puts both Petey and Li’l Petey to sleep via sleep gas, after they visit him in custody. He then steals Petey’s identity and kidnaps Li’l Petey in the latter’s sleep.
  • The Alistair Maclean novel The Golden Gate has aerosol gas that causes instant unconsciousness. The criminal mastermind planning The Caper wants to avoid killing anyone for publicity reasons in case he doesn't get away with it.
  • Subverted in the opening scene of A Piece of Resistance by Clive Egleton. La Résistance use a knockout gas to remove an innocent bystander, who then dies of a heart attack.
  • Fighting Slave of Gor: Jason Marshall and his date Beverly are taken out by knockout gas in the backseat of a specially-prepared taxi. They were only after her, but he forced his way into the cab when she was trying to end the date.
  • In Harry Harrison's The Stainless Steel Rat series, both local law enforcement and Slippery Jim use Knock-out Gas with great abandon, although slightly more realistically than is usual in fiction. Jim makes sure to use nasal filters or a mask to avoid breathing it in himself, it's usually invisible rather than brightly colored, and there are numerous different types, with different effects, speed of action, duration and after-effects.
  • In Larry Niven and Jerry Pournelle's Oath of Fealty, The Todos Santos arcology uses knockout gas as part of its internal security system.
  • In Little Green Men, the "aliens" use a gas named sevoflurane to anesthetize their abductees, usually with added ammonia and cinnamon scent.
  • Anne McCaffrey's Pegasus series has Law Enforcement & Order use 'anesthesine gas'.
  • Sleeping gas was one of the staple weapons Butler Parker used. Occasionally, though rarely, he also was at the receiving end of a dose - in which case often one of his ballpoint pens containing a breathing mask came in handy.
  • Used in The Commissar by Sven Hassel to immobilize a Soviet prison camp for The Caper. It's pointed out the gas can only be used in confined spaces "otherwise the whole German army would have been put to sleep long ago." Several people start waking up early and have to be killed by the Psycho for Hire ex-NKVD man who's helping them.
  • Zig-zagged in Artemis, the meltdown of the smelter produces chloroform and releases it into Artemis' air supply, knocking everyone out. But, it's not harmless and our protagonists have to flush the air before it kills them.
  • In John Christopher's novel Year of the Comet, the two protagonists get entangled in power-plays between the mega-corporations that rule their post-World War III world, leading to them twice getting gassed and carted off to new locations. Just to add some variety, at another point they are also clubbed unconscious.
  • The Machineries of Empire: Kujen's flagship is rigged to deploy knockout gas everywhere except his hermetically sealed private suite in an emergency. Though it's ostensibly nonlethal, it needs an antidote and still causes lasting ill effects; several staff die from accidents like drowning in their baths; and Dhanneth is hospitalized with a serious allergic reaction.

    Live-Action TV 
  • The Green Hornet has as one as his main weapons, the "Hornet gun", spraying "Hornet gas" that would knock out mooks with one sniff. This is a carryover from the original radio series and 1940s film serials.
  • The Prisoner (1967). The sleeping gas used on Number 6 in his apartment in the first episode (and each episode's opening title).
  • Doctor Who. The Master uses this to subdue the Doctor and Jo Grant when they break into his TARDIS in "Colony in Space"
  • A constantly-recurring staple of both villains and heroes on Batman (1966), most often in the form of colorful Knockout Gas.
    • "The Bookworm Turns". The sleeping gas released by the Bookworm's booby-trapped book renders Robin unconscious in seconds.
    • "While Gotham City Burns". The Bookworm uses a package booby-trapped with sleep gas to render Alfred and Aunt Harriet unconscious so he can steal a book from the Wayne manor library.
    • In "Hi Diddle Diddle" and "Smack in the Middle" the Riddler uses an aerosol can of sleeping gas to put Robin to sleep.
    • "The Ring of Wax". The Riddler renders a guard unconscious with gas released from a candle.
    • In "The Joker Goes To School" the Joker tampers with a milk machine so that it shackles the Dynamic Duo, then releases knockout gas before they can free themselves.
    • Batman, himself, used it several times when there was a reason he had to bring someone to the Batcave. He even had a can of Bat Awake that could reverse the effects just as quickly.
  • Simon & Simon episode "Under the Knife" has A.J. gassed in a hospital room and in danger of unnecessary surgery when the brothers get too close to the truth in a malpractice scam.
  • Star Trek
  • The Wild Wild West
    • In the episode "The Night of the Sudden Death", invisible gas pumped in from a gaslight lamp with an unspecified additive is used to fill a very large U.S. Mint set and knock out several people within seconds.
    • In another episode, Gordon uses Knockout Gas himself, but he's still dissatisfied with it because it's too visible.
  • In the "Biology 101" episode of Community, a variant of Knockout Gas intended for monkeys ("Chimpan-Zzz" brand) is pumped into the Greendale air vents. It turns out to work on humans too, with the additional side effects of causing hallucinations and references to 2001: A Space Odyssey.
  • In the Stargate Atlantis episode "Inquisition", Atlantis' first team is taken out by Knockout Gas in a cell, before being moved to another planet through the Stargate so the rest of the expedition can't find them.
  • In The Aquabats! Super Show! episode "Cobraman!", while the team is trapped inside the Battletram by Carl, who forces the team to watch the MC Bat Commander fight the Cobraman, Jimmy the Robot detaches one of his hands and remote controls it so as to access a knockout gas button that, when activated, knocks out Carl and the rest of the team inside (Jimmy, being a robot, isn't affected by the gas), effectively freeing the team from Carl's clutches.
  • Skouras tries to use this (or possibly Deadly Gas, but the fact that he had henchmen in gas masks with guns on hand suggests that the gas itself wouldn't have killed her) on Dani in the finale of Believe. She manages to neutralize it with her Psychic Powers, something that even with all of his years studying people like her he didn't think was possible.
  • MacGyver (1985): An instantly sedating knockout gas was one of the weapon systems on the attack helicopter in "Honest Abe".
  • Person of Interest.
    • In "Lady Killer", Root escapes from the mental hospital this way, as per the page quote.
    • In "Razgovor", Shaw and the Victim of the Week do an Air Vent Escape in an old apartment building, so The Mafiya thugs chasing them do a field improvised version by puncturing the air conditioning system, causing chlorodifluoromethane to flood into the vents.
  • The Professionals. In "Need to Know", the KGB snatch a Double Agent from a Vulnerable Convoy, but don't want to invite retaliation by killing British agents, so use stun gas instead. We later discover the snatch is a Batman Gambit by George Cowley, who is covering his men with a sniper rifle in case the KGB decided to use more lethal means. Bodie and Doyle weren't in on the plan, so aren't happy when they regain consciousness.
  • Fleming: The Man Who Would Be Bond. Ian Fleming demonstrates a fountain pen that sprays knockout gas (among other gadgets) for some visiting top brass. Unfortunately, he does this by gassing his Sassy Secretary, who is not amused when she wakes up.
  • In one episode of Drake & Josh, Megan puts out a canister of knockout gas when the boys keep her up at night with their arguing. She uses another one at the end of the episode when they get into another argument.
  • Sona gas is mentioned specifically in the Blake's 7 episodes "Mission to Destiny" and "Pressure Point". Presumably there are other kinds. In "Volcano", Tarrant and Dayna are walking through a BBC Quarry when aliens on the cliffs above fire a narcotic gas over their heads that drifts down as mist and knocks them out. A concentrated dose from the same weapon is later used as a Deadly Gas to kill someone.
    Tarrant: It can't be raining? (keels over)
  • Wonder Woman (1975): Wonder Woman is taken down many times this way. Knockout gas and chloroform were the only reliable method of fighting her when she was not disguised as Diana Prince.
    • In "Judgment from Outer Space (Part 1)", a Nazi mole fires a gun at her feet that turns out to be a knockout gas grenade.
    • In "Baroness Von Gunther", the eponymous Baroness sprays Wonder Woman with knockout perfume.
    • In "The Feminum Mystique Part 2", the Nazis take over Paradise Island. When they discover that all of the women can overpower them, they turn to hand thrown knockout gas grenades.
  • The Barrier: A truck secretly transporting a group of children between two locations has its back filled with a gas that puts all its occupants asleep, except for the guard wearing a gas mask.

    Tabletop Games 
  • Dungeons & Dragons.
    • At the end of module A3 Assault on the Aerie of the Slave Lords, a green gas (the "Smoke of the Little Death") is used to knock out the PCs so they can start the next module as the Slave Lords' prisoners.
    • In module S1 Tomb of Horrors, there's an area filled with sleep gas. Everyone who enters the corridor immediately falls asleep for between 20 minutes and more than an hour, during which time they will probably be squashed flat by the magical equivalent of a steamroller.
    • Module S3 Expedition to the Barrier Peaks has sleep gas grenades. Anyone exposed to their gas falls asleep for 20-50 minutes.
  • Shadowrun. The various Neurostun gasses are often used to take out shadowrunners without killing them.
  • Judges Guild supplement Revised Guide to the City State. The Temple of Bubastis has a huge hollow brass idol with a 4th level magic user inside it. Worshippers drop treasure before the idol and then leave. If they return too soon, the magic user will pull a lever and fill the area with sleeping gas.
  • Traveller
    • Double Adventure 3 Death Station. One of the items of equipment available to PCs was Tranq Spray, a small aerosol can that sprayed a tranquilizing mist. When used at close range, it calmed the target down and then put it to sleep.
    • Adventure 8 Prison Planet. The guards in the Imperial prison on Newcomb can release knockout gas to neutralize rioting inmates. The gas is not stopped by a standard filter mask.
  • Marvel Super Heroes supplement Uncanny X-Men boxed set "Adventure Book".
    • In chapter 4 "Time Out" the PCs are at a charity basketball game when the supervillain Arcade performs a Knockout Ambush by flooding the gymnasium with sleep gas in order to capture them.
    • At the end of Chapter 8 "Terror in the Amazon" the PCs are subjected to another Knock Out Ambush by Arcade's sleep gas the same way they were in Chapter 4.
  • Gas Grenades are a weapon that can be used by the crew-player in the board game.The Awful Green Things From Outer Space; the effect on the Things (good, bad or indifferent) is randomly determined for each game, but any crew present when one gets set off are knocked unconscious for a turn.
  • Champions Organization Book 2 PRIMUS and DEMON. Demonflux tries to capture the superhero Sureswift by luring him into a warehouse and flooding it with a sickly-sweet gas that causes unconsciousness.
  • Top Secret Companion, adventure "Operation Meltdown". There are two sleep gas traps in the houses occupied by the main villains that render anyone without appropriate protection unconscious.
    • In an elevator, pushing one of the buttons releases sleeping gas through vents in the ceiling.
    • A secure vault will release sleep gas if one of the necessary combinations to open it is not entered correctly.

  • In Animal Crackers, when Doucet threatens to arrest people unless they produce the painting, the Professor sprays everyone else with knockout gas, and after lying down beside a girl sprays himself. For no particular reason, this became the ending of the film version.

    Video Games 
  • Thief: The Dark Project has Gas Arrows: shooting a mook will knock him out even if he's fully aware of your presence (and thus would only get annoyed by the Blackjack). Shooting the ground has an area effect, knocking out everyone within a meter or so.
    • Thief II: The Metal Age adds in Gas Mines — a mix of the Gas Arrow and Mine that can be used in the same way, but only as an area effect and only after a mook steps on it.
      • Thief: Deadly Shadows replaces the above with the Gas Grenade. It works like the Gas Mine, but is instantaneous.
  • Deus Ex: Human Revolution has Gas Grenades as one of the weapons in the pacifist player's arsenal. It's a generally useful tool for knocking out multiple enemies where tranqs, stun guns, and takedowns are just inappropriate, and everything else is overly lethal.
  • In the Apple II-era game Infiltrator and Infiltrator II, you use a canister of knock-out gas to deal with enemy mooks (and I don't mean hitting them with the can). Works instantaneously every time.
  • In The Legend of Tian-ding, the Geisha dancer turns out to be a master thief, Kaguya, who reveals herself by dropping a Smoke Bomb full of nerve gas knocking out everyone in a room in order to steal a valuable Macguffin item. Unfortunately for her, you're a master thief yourself (of the Just Like Robin Hood variety) who beats her to the punch by pickpocketing Kaguya's intended victim, escaping before her gas affects you. She then challenges you to a duel leading to a difficult boss fight.
  • The RuneScape quest "The Great Brain Robbery" has a section where Harmony Island is covered in knockout gas. You have to wear a scuba-diving helmet or you'll be knocked unconscious.
  • In Mega Man Battle Network 5, at the very beginning of the game, Lan, Dex, Mayl, Yai, and Yuuchiro are knocked out with bright pink sleeping gas, Yuuchiro is kidnapped, and everyone's navies except Megaman are stolen.
  • Metal Gear Solid V: The Phantom Pain allows players to develop and use sleeping gas grenades, which can knock out almost any enemy guard in seconds. There are also sleep gas variants of the game's grenade launchers, though Gas Mask Mooks are immune to all forms of sleeping gas.
    • There's also the AM A114 Riot Pistol, which disperses a small cloud of sleeping gas where its shots land.
  • Pokémon has the moves Sleep Powder and Spore. The only differences are the accuracy and the PP.
  • In Sonic Adventure, Eggman gives Sonic and Tails a quick snort of purple sleeping gas outside the casino. Puts 'em under in seconds flat, too!
  • The later Syphon Filter games have DormaGen gas grenades.
  • Pony Island: At the end of Act II, the arcade machine spews sleeping gas at the player, causing a 300-year Time Skip. Not that it matters in Limbo; the only difference being that Pony Island now looks nicer.
  • Sherlock: The Riddle of the Crown Jewels requires you to hold your breath before breaking an ampoule filled with a knockout gas. You then have an extremely tight window to do what's necessary with the two knocked out enemies.
  • The Desperados series has flasks of green gas, which render anybody unconscious within a small area.
  • In Mr. Shifty, Mr. Shifty is ambushed with this early on.
  • Several monsters from Monster Hunter can do this, inflicting the Sleep status if the affected Hunters don't chug an Energy Drink fast enough.
    • Monster Hunter 3 (Tri): Uragaan has pores on its back that it can use to release sleep-inducing gas. The Crystalbeard variant introduced in Monster Hunter Generations launches gems from its tail that can be mined, and each material they give you sells for 10,000 Zenny a pop. However, said gems can ALSO release sleeping gas at random, so you'd best have some Energy Drinks handy or you're in real trouble.
    • Monster Hunter: World:
      • Radobaan, Uragaan's smaller cousin introduced, has a back that can be mined for bones. However, one must be careful when doing so, as it can also release sleeping gas from its back.
      • Paolumu has a subspecies introduced in the Iceborne expansion, Nightshade Paolumu, who mixes chemicals in its air sac to produce a sleep gas, which it can then shoot out in lingering clouds.
  • Caves of Qud: The Sleep Gas Generation mutation lets you (and random creatures that can get it) puff out a large mass of sleeping gas that will force those that inhale it to roll Toughness against falling asleep right on the spot. It's quite useful, as it keeps them down a while and vulnerable to your attacks, but it doesn't work on anything that doesn't breathe or sleep.

    Visual Novels 
  • In Nine Hours, Nine Persons, Nine Doors and its sequel, Virtue's Last Reward, the main characters are all sedated with a gas called Soporil, after which they are kidnapped to play the Nonary Game.
    • In the first game it's a huge plot point that it works like this. Pretty much the first anesthetic gas that you don't have to dose properly to avoid overdose.

    Web Animation 
  • Lobo (Webseries): Sunny Jim uses this on Darlene Spritzer in "Lobo Is A Four Letter Word".


    Web Original 
  • In Curveball, Agent Travers rigs the fire sprinklers in his office to spray an instantly paralyzing neurotoxin to deal with unfriendly visitors. One second he's kicking his desk in a certain spot, the next, everyone is wondering why they're suddenly on the floor. Agent Travers is also paralyzed by the gas, but since he took the antidote beforehand, it wears off him in just a few minutes.

    Western Animation 
  • Batman: The Animated Series: MAD parodied the tendency of villains to use this.
    Bats-man: "Cattywoman's releasing some horrible gas!"
    Robin (drawn to look like Calvin): "That might be me, Bats-Man. We did stop at Taco Bell!"
  • The Simpsons:
    • In the "Treehouse of Horror III" segment "King Homer", the giant ape is subdued by knockout gas, but not before eating someone.
    • In one episode where the Simpsons go to Cuba, Grampa's CIA agent girlfriend hijacks their return flight and floods the passenger cabin with knockout gas. Homer is conscious long enough to express relief that he can finally get some sleep on one of these flights.
    • In "'Round Springfield", Dr. Nick Riveria is putting Bart to sleep for surgery and accidentally puts himself to sleep as well.
    • "The Computer Wore Menace Shoes'': Knockout gas is used to subdue Homer so he can be taken to the island. Used again at the end of the episode to kidnap the entire family and take them to the island.
    • Smithers uses knockout gas on Mr. Jones in "Marge Gets a Job".
  • The Fairly OddParents!
    • In the episode "Totally Spaced Out", Mark Chang uses this on Vicky at the episode’s start and kidnaps her all because of wish made by Timmy to get rid of Vicky and she remains unconscious throughout the episode.
    • In "Boys in the Band", Chip gets hit by it twice, first by Vicky to kidnap him, and later by Timmy so he can get him to the concert without revealing his secret.
    • In "Class Clown", the seemingly harmless plant uses this on Trixie to knock her out prior to eating her heart.
  • Jonny Quest TOS episode "The Quetong Missile Mystery". Sleep gas knocks out General Fong in a couple of seconds.
  • Family Guy Peter gave his rival a statue of himself that sprayed "Crazy Purple Knockout Gas!". When it fails to go off, he nudges it with his foot several times before it sprays the gas backwards at him.
  • She-Ra: Princess of Power once features a scene where villain Hordak sprays one of the heroes with some sleep gas from his Swiss Army Hand. The hero gets off an exclamation and keels over. Hordak then comments that he's going to have to have a word with his scientists; the victim shouldn't have had time to say anything before succumbing.
    • Shadow Weaver also uses spells that consist of "sleep mist" which is magical Knockout Gas.
  • He-Man and the Masters of the Universe (1983): Skeletor has spells that function as this.
  • Space Ghost episode "The Looters". Brak uses a sleep gas missile on a ship.
  • In one of the Gorillaz short animated idents, 2D is knocked out cold by just a whiff of gas.
  • Darkwing Duck uses a gun that could fire knock out gas (among other things). Due to the character being a little clumsy, he knocks himself out once or twice.
  • In Wakfu season 2, the Justice Knight captures fugitives with his Justice Train by trapping them inside the wagon, which then fills with a golden Knockout Gas. The effects are shown to be immediate even with the heroes.
  • Subverted in Archer, when Cyril thinks he's delivering a dose:
    Cyril: (procuring a briefcase) I got the ten million in bearer bonds.
    Spelvin: Unbelievable!
    Cyril: Well, I...
    Spelvin: No, I mean literally. I don't believe you. I suppose this is full of knockout gas or something... (opens briefcase to reveal a single cupcake)
    Cyril: Apparently not.
    Archer: (kicking in the door) Exactly! Because I don't know if that's even a real thing!
  • One of Kim Possible's gadgets is a "lip gloss" container that actually holds a "super-stink" formula created by Wade using his dad's dirty socks.
  • The My Little Pony: Friendship Is Magic episode "MMMystery on the Friendship Express" has the cake-guarding Pinkie Pie taken out with this by a Tuxedo-and-Martini superspy in one of Pinkie's Imagine Spots.
    • In the season 4 premiere, Twilight gets knocked out by some weird black plants when they unleash some blue gas on her.
  • One of the many types of gases used by the vile borg, Noxious in Skysurfer Strike Force.
  • The Galaxy Trio episode "The Duplitrons". Meteor Man is taken out twice by sleep gas: once while he's flying in a rocket pod, the second time after he wakes up in the Duplitrons' base.
  • Fantastic Voyage. At the beginning of "The Master Spy" the title character knocks out Professor Carter by using a gas gun to fire sleeping gas into his face.
  • Milo Murphy uses this to deal with animals such as tigers and polar bears.
  • In X-Men: Evolution, Wolverine proposes that the mansion's security be tightened with the use of poison gas sprayers to prevent external access through the ventilation system. He settles for knockout gas after Storm voices an objection to this.


Video Example(s):

Alternative Title(s): Sleeping Gas


Dr Nick Puts Himself To Sleep

While putting Bart to sleep for surgery, Dr Nick Riveria accidentally puts himself to sleep as well.

How well does it match the trope?

4.78 (9 votes)

Example of:

Main / KnockoutGas

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