Before ironclads came on the scene, ships were extremely flammable. However, since they also had ready access to water, exploiting this required something special. Enter the Byzantine Empire, who developed the Trope Namer, a type of fire that was impossible to extinguish with water. Ever since, many works involving pre-gunpowder navies involve some form of it.
Numerous naval incendiaries exist, but to properly qualify as Greek Fire they must possess certain characteristics.
- It must manifest as a burning liquid or putty.
- It must be sticky, so it cannot be scraped off skin.
- It frequently burns sickly green or another nonstandard color.
- Optionally, the method of manufacture may be a closely guarded secret.
- Most critically, it must be impossible to extinguish with water. Smothering it with sand or similar may or may not work.
Greek Fire is usually also universally feared for obvious reasons, as an ancestor of sorts to napalm and modern flamethrowers. The exact recipe was a state secret known only to two families: the Kallinikos family, who were descended from its original inventor, and the Imperial family. As a result it's been lost to history. However, some putative components include some kind of naphtha (light petroleum) as the key ingredient, quicklime (calcium oxide reacts explosively with water), resin for the viscosity, sulphur, potassium nitrate, and, according to some scholars, gunpowder. Preparing Greek Fire was an extremely dangerous process given its volatility, also requiring complex technology for the period for petroleum distillation. That's why the secret was bestowed to only a few.
Note that it is not exclusively used at sea, but a combination of the relative ease of employment due to era boarding tactics and the ability to destroy ships entirely through secondary wood fires, leaving nowhere to escape, make it far more effective and terrifying at sea.
- The first two issues of DC Comics' Blue Beetle series of the 1980s has Ted Kord dealing with the Incendiary Man who uses this to burn down his target buildings, all for the sake of getting even with the city of Chicago's fire department for failing to notice him when he was trapped in a burning building.
- Greek Fire is used by Blackbeard in Pirates of the Caribbean: On Stranger Tides.
- Wildfire from A Song of Ice and Fire is unquenchable by water, lights anything used to smother it on fire, and burns brilliant green. It was used in the battle of the Blackwater and was essentially the only reason Tyrion won. Its production is a secret well-guarded by the Alchemists' Guild, but there are strong implications that some sort of magic is involved. Storage is extremely dangerous, and it's eventually revealed that the Pyromaniac former "Mad King" Aerys II had thousands of pots of it buried in secret throughout the city in order to burn the whole place down if it was captured, and that this discovery was the reason Jaime Lannister killed him before he could give the order. Fridge Horror comes into play when you realize that there is a real chemical that can do this without magic and is every bit as dangerous: chlorine trifluoride.
- Leviathan has Phosphorus rounds, which display all of the characteristics, though they're used against hydrogen filled fliers
- The Recluce saga includes Chaos fire, which is magically generated. It is especially feared because, in addition to the standard characteristics, it can be created inside steam engines and loaded cannons.
- The Council Wars series fills this role with Napalm, although after the first couple uses they get extinguisher foam on all ships, somewhat reducing both effectiveness and the terror factor
- The Akkadian fire in the Dragon Jousters book Sanctuary.
- Eldest: green fire is used on an arrow fired at Roran's ship, forcing the crew to hack away ignited portions.
- The honeyfire demonstrated by the Herders in the Obernewtyn Chronicles appears to be this.
- The blazebalm used in the Tortall Universe fits most of the requirements. It is a flammable jelly-like substance that is often used as an explosive weapon; it is particularly useful against spidrens and other immortals.
- Used literally in the Percy Jackson and the Olympians series and its sequel, in which Greek Fire is a magical substance that burns green and is lethal to monsters and demigods alike.
- Timeline: Professor Johnston is forced to recreate Greek Fire for Lord Oliver, he succeeds in making something that ignites when exposed to water.
- Metamor Keep: the Kingdom of Whales has Greek Fire, the name "Greek" was eventually retconned to be the name of the inventor.
- Phil, a Whalish prince who was visiting Metamor at the time of the Battle of Three Gates, attempted to assist in the fight with Greek fire, but there was an accident and he was covered in the stuff. The flames disappeared when the Curse transformed him into a rabbit, but if the Curse is ever removed or suppressed the fire returns. And the experience traumatized him so badly he reverts to a feral state every night.
- The Gentleman Bastard universe lacks gunpowder and firearms, yet "alchemy" has devised a type of inextinguishable incendiary bomb which burns white hot like blazing sun and can burn a large man-of-war in minutes. It's so destructive that warship captains avoid its use in combat since storage aboard ship would be too dangerous.
- Wise Phuul: rulion burns white, and is considered so dangerous its manufacture has been banned via diplomatic treaty.
- The Witchlands has seafire, which is basically traditional Greek Fire turned Up to Eleven in power. How it's made is not said, but it's Firewitched in some way to make it stronger, and the sheer mention of it is enough to terrify experienced sailors.
- One of the low-tech alien races in Ranks of Bronze have what seems like Greek Fire, the faction defending a fort from the legion pour it down murder holes and toss pots of the stuff at them.
- In The Traitor Baru Cormorant, Falcrest's dominance at sea is ensured by the "Navy Burn", a sticky, highly flammable oil that burns green and can't be extinguished with water. In fact, being an oil, spilled Burn floats on water and sets the sea on fire too. It can be sprayed from siphons, like Greek fire in real life, but its more often used to arm Falcrests signature gunpowder rockets, significantly increasing its range. No other maritime power fields anything remotely as lethal — the Oriati Mbo's cannons are good at putting holes in wooden ships but bad at actually sinking them, while a single Burn missile can turn a warship of any size into so many cinders.
- Game of Thrones, the live-action adaptation of A Song of Ice and Fire shows Wildfire in all its horrifying brilliance in the penultimate episode of the second season, "Blackwater". It's portrayed as a Fantastic Nuke, complete with a mushroom cloud out the top of the massive green fireball. Ships are completely obliterated in the initial blast, and the green inextinguishable fire understatedly lingers for much longer.
- Wildfire appears again in the season six finale, "The Winds of Winter" as part of Cersei's plot to evade her forthcoming trial and destroy her enemies in one fell swoop. The blast is even more destructive than the one in "Blackwater", annihilating the Great Sept of Baelor in a blinding flash of green, along with hundredsif not thousandsof people inside and for several blocks around.
- Fluff occasionally mentions the High Elves of Warhammer having a substance called "Alchemist's Fire" designed for use against other ships (though it can be utilised for other purposes) which burns white and whose recipe is a closely-guarded secret.
- Dungeons & Dragons has alchemist's fire, though most versions are not waterproof it is still sticky and burns when exposed to air. Some supplements do have waterproof versions.
- Ironclaw: The Book of Horn and Ivory has an incendiary alchemic weapon called "aqua vitae" (historically concentrated alcohol).
- Warhammer 40,000: The Imperium had Phosphex Weapons, which are based on real life White Phosphorus except even more volatile. "Had", because one Tech-Priest was so horrified by Phosphex that he destroyed the STC for Phosphex weaponry, considering it too horrific to use. The last true Phosphex weapon, which was used to execute said Tech-Priest, is thus a precious relic of the Adeptus Mechanicus. The Tech-Priest wasn't the only one who hated phosphex. The Primarch Vulkan, who normally favored a Kill It with Fire approach to problems, refused to use it considering it something that should have remained in the Dark Age.
- Age of Empires and Age of Empires II had fire-ships that used the historical Greek Fire, projected from hoses. Although short-ranged, they did deal substantial damage to enemy ships. Unsurprisingly, the inventor, the Byzantine, has some of the best fire-ships with its faster attack speed and gaining extra range from the Greek Fire unique research.
- Age of Mythology: The expansion The Titans adds the Atlantean civilization, which has the fire ship unit, the equivalent of hammer ships to be used against arrow ships, only it uses Greek fire instead of a hammer.
- Assassin's Creed: Revelations: Ezio burns down a good part of the Ottoman navy as it's blocking the port on his way to Cappadocia.
- Medieval II: Total War has fire ships for the Byzantine Empire. The Crusades campaign in the expansion also has Greek Firethrower units that use it in handheld flamethrowers.
- Civilization: The Byzantines get the fire-shooting Dromon galley as a unique unit in both Civilization III (when they appear in the Conquests expansion) and Civilization V (when they appear in the Gods and Kings expansion).
- Rise of the Tomb Raider: The Deathless Ones make extensive use of Greek Fire for fire arrows, grenades and placed explosives in the form of large jars. Their version of the stuff burns bright-blue, and their obsession with it is well-justified, given how they're undead descendants of a religious cult that fled the Byzantine Empire in the 10th century. Lara can acquire the recipe late in the game to upgrade her own fire arrows with increased damage against armored targets.
- Though Crusader Kings II has no naval combat, if you play as the Byzantine Empire you may hit an event chain where the Empire's supply of Greek fire is stolen.
- Where in Time Is Carmen Sandiego? (1997): The fifth level features a siege against William the Conqueror's castle where the Anglo-Saxon are firing a ballista whose spears are tipped with Greek fire.
- The Byzantine Empire developed the Trope Namer, which proved instrumental in major naval victories, including two sieges of Constantinople. Nobody is sure exactly what the original recipe was,note , and "Greek fire" seems to have become something of a catch-all term for any Fire-Breathing Weapon, but the original stuff was some sort of liquid that ignited spontaneously in contact with water. The Byzantines initially delivered it by flinging clay pots at enemy vessels that would smash up on the decks and catch fire, they eventually developed a "siphon"—really more like a large, primitive syringe or bicycle pump—to shoot jets of fire at the enemy. It was a complete Game-Breaker in naval combat well into the early days of Wooden Ships and Iron Men, only being made obsolete when cannon that could reliably hit a target outside its very short range became widespread.
- White phosphorus is a modern example, nowadays it is used for smokescreens as well as incendiaries.
- Flamethrowers and the infamous napalm fit this trope all too well.
- Burning sugar fits this trope as well, which adds an extra dimension of hazard to fires in sugar refineries and jam factories. A British sugar refinery was bombed by the Luftwaffe in 1940 with few immediate fatalities - but local hospitals were overloaded by casualties with 85 - 90% burns, most of whom took days to die.