Everything's more awesome when it's on fire. Unfortunately, in Real Life most ordinary objects, structures, and creatures are not particularly flammable. Even many of the materials that we keep around specifically for burning, such as charcoal and firewood, take time and effort to get a real blaze going. But hey, since when has reality gotten in the way of a good story?
In fiction, it's common for anything that might be even remotely flammable— or even some things that aren't— to behave as though they were soaked in kerosene. The merest touch of a flame, spark, or other source of ignition will set it ablaze, and it will never burn itself out but continue burning indefinitely, usually setting anything else it comes into contact with on fire with similar alacrity. One of the most common forms of this is when fire touches gasoline in open air, and the gas acts like napalm (in Real Life, gasoline needs to be mixed with oxygen in a precise ratio to burn, and won't do so very well in the open air).
This often overlaps with Hollywood Fire, creating a near-instant raging inferno that nevertheless leaves the heroes conveniently untouched. It also almost always applies to any creature with a weakness to fire, such as most types of undead.
- Vampires in Twilight seem to have varying degrees of flammability. In the first movie, the protagonists kill and burn a vampire in a large fire. In the third film, Edward throws a lighter on a recently killed vampire. Both methods of burning resulted in vampire flambé. Even the latter's clothing rapidly burned away.
- The Ring Wraiths in Lord of the Rings will burst into flames if they come in contact with a fire source. Aragorn uses this to an incredibly effective degree when he lights up half of them and hurls the torch so hard that it embeds into one's face. Doesn't really seem to deter them for long, though.
- In Star Wars: Revenge of the Sith, Obi-wan kills the cyborg General Grievous by using a discarded blaster to shoot Grievous' few remaining organic parts. He quickly catches on fire, and Grievous' face explodes.
- Indiana Jones:
- In Raiders of the Lost Ark, Marian's bar catches fire incredibly quickly. Granted, it appears to be mostly wood construction, but unless her patrons make a habit of spilling whole bottles' worth of her very highest-proof spirits (most liquors are not flammable) absolutely everywhere to make the fire spread as quickly as it does, there's no reason the entire structure should have burned down other than Rule of Cool.
- It gets even more ridiculous in Indiana Jones and the Last Crusade when a similar scene (very small fire caused by a dropped cigarette lighter escalates comically quickly into a giant blaze) happens in a stone castle.
- In The Green Hornet Strikes Again!, the ocean liner "Paradise" must have been made from flash paper. In the time it takes the Hornet to force a one-page confession from a crook, a fire in one of the holds takes over most of the ship.
- Inverted in The Artist: When George burns the film reels, they take quite a while to get a good blaze going. However, since film of that era really was made of incendium (aka nitrate), it should have turned into a massive fire in seconds. Nitrate films (made prior to the introduction of Cellulose Triacetate (safety) film in 1948) had to be stored in thick-walled concrete bunkers because they were so flammable. This video shows some examples in its first 2 1/2 minutes, and an even more spectacular example starting at 4:25. Safety film is non-flammable. Get it hot enough and it will melt, but it won't burn, as this video shows.
- Dave Barry states in his home improvement parody book The Taming of the Screw that you can make softwoods (e.g. pine) burst into flames by merely dropping it. (In contrast, hardwoods are very safe, since they automatically extinguish themselves when you light them.)
- Game of Thrones:
- Jon Snow turns a wight into a walking bonfire in short order by smacking it around a little with a lit torch. Note that this is not some dried-out, thousand-year-old desiccated mummy, but a very fresh corpse that also happens to be frozen solid at the time.
- Stannis' supplies (and horses) in Season 5 appear to be Made of Incendium if the ease by which a handful of men can turn them into an uncontrollable inferno without anybody noticing until it's too late is any indication, leading some fans to speculate that it may have been an Inside Job by Melisandre (whose magic could have done so much more plausibly) aimed at making Stannis desperate enough to sacrifice his daughter to R'hllor.
- In "Game Of Thrones S 6 E 4 Book Of The Stranger", the khals apparently hold their most important meetings in gasoline-soaked huts, if the ease with which Daenarys can set the place ablaze and kill them all is any indication.
- In iCarly, it's a Running Gag that Spencer can set anything on fire by accident, even things that shouldn't be flammable, even without using fire. Not only is everything made of incendium... it's magic, too.
- In the Star Trek: Deep Space Nine episode "Progress," Kira barely has to touch Mullibok's house with a lit torch to set it to burning merrily.
- Kamen Rider:
- In Kamen Rider Faiz, defeated Orphonochs erupt into blue fire and then crumple into dust.
- AdventureQuest: Werewolves originally had a large weakness to fire. Eventually each update made them even weaker to the point to where they would burn from the weakest fire sources. Even normal wolves aren't spared from the blazing weakness.
- Left 4 Dead series: The Infected in Left 4 Dead can be lit up from somewhat understandable sources, such as Molotov cocktails and to a stretch, incendiary ammo. However it's most obvious when the zombies toast themselves doing relatively not-deadly things such as vaulting over burn barrels or stepping on smoldering coals. Said things at their WORST would inflict minor burning and welting. The playable "Special Infected" can be set ablaze by small sources as well, and will actively burn for up to an entire minute (depending on HP) before suddenly dropping dead; rendered to a charred heap.
- Half-Life The headcrab zombies burn pretty easily in the sequel, though everything else does as well. Road flares and even small debris fires will send even heavily armored Combine troops aflame.
- Enemies in the game adaptation of The Thing (2002) will ignite at small fire sources. They may light each other on fire if they collide with one another, and may even light the player up as well.
- The Legend of Zelda:
- While donning the Zora's mask in The Legend of Zelda: Majora's Mask, contact with any fire source will immediately kill you, and the last few seconds before continuing shows Zora Link bursting into flames and collapsing.
- The Keese in the The Legend of Zelda: Ocarina of Time are extremely flammable. In fact, they'll often deliberately light themselves on fire to do more damage to the player!
- Bow Master: In the third game, killing an enemy with fire results in it turning slowly into ash from the feet up, leaving only a charred skeleton wearing a helmet.
- Evolve has several fires burning in the ruined structures of its maps that never die down and don't seem to have any fuel source.
- Mass Effect 2 and Mass Effect 3: Any unshielded organic enemy will light up and immolate when hit with Incindiery Ammo or the Incinerate tech attack. Never mind that they might be wearing ablative body armor, have chitinous armor or a cybernetic skin weave. They all go up in flames.
- The Simpsons: In "Homer the Smithers", Homer, sitting in for Smithers while he's on vacation, tries to make breakfast for Montgomery Burns only to repeatedly set it on fire. Even when he pours a bowl of corn flakes and milk.
- Played for Laughs in Futurama:
Zoidberg: How could this happen?!Hermes: That's a very good question!Bender: So that's where my cigar was.
- In one episode, Doctor Zoidberg tries to re-coil a slinky after Bender has straightened it into a straight wire. It goes down two steps, falls over and then bursts into flame.
- Lampshaded in another episode where Zoidberg claims a giant conch shell on the bottom of the ocean as his home. Later in the episode they return to it to find it's burned down, leaving only a charred framework.
- Spongebob Squarepants: One episode has a gag where Patchy leaves a note for Spongebob, but the ink runs in the water. As Spongebob notes, whoever wrote it clearly didn't consider the physical limitations of living underwater, and they might as well throw it into the fire. Which they do.