Beast of Battle

"Chidren of the Camp are we, serving each in his degree;

Children of the yoke and goad, pack and harness pad and load

See our line across the plain. Like a heel-rope bent again,

Reaching, writhing, rolling far. Sweeping all away to war!

While the men that walk beside. Dusty, silent, heavy eyed

Cannot tell why we or they, March and suffer day by day.

Children of the Camp are we, serving each in his degree;

Children of the yoke and goad, pack and harness, pad and load"

- Parade song of the camp animals by Rudyard Kipling

In Speculative Fiction, especially video games, there's a habit of utilizing animals as full-fledged war machines, rather than just mounts or for pulling. This makes a fair bit of sense, especially in Fantasy worlds: If there are three-ton, fire-breathing dinosaurs in your kingdom, sooner or later somebody's gonna get the idea to unleash them on people they don't like.

The creature either uses its natural abilities and/or has various platforms and/or instruments of destruction lashed to its side or across its back that human(oid) soldiers can use in battle. This can be as simple as a Howdah or other platform from which your soldiers can fight, but weapons like ballistae, cannons, and other mechanisms are also common.

Depending on their intelligence, they may be capable of working independently.

See also Dragon Rider, Horse of a Different Color, Weaponized Animal.

Anime/Manga

 * Kacchū no Senshi Gamu, a series by Yoshihiro Takahashi, features a clan of warriors who are allied to a pack of samurai dogs who have telepathic powers, can speak human language and wield swords better than the humans in the story. Yes, the entire series pretty much runs on Rule of Cool.
 * Pokémon Lucario and The Mystery of Mew showed a number of battle scenes in ancient times, showing that Pokemon were understandably a big factor in armies a long time ago.
 * Zoids dips a paw into this territory, given that the titular Humongous Mecha also happen to be part of the local wildlife. No, we're not quite sure how that works...
 * The Tailed Beasts in Naruto.
 * In the Monster Rancher anime, the series' Mons were originally genetically-engineered pets by an advanced Precursor civilization, then were utilized as soldiers and weapons when war broke out between two rival superstates. The series Big Bad was developed as a type of Superweapon, and you can guess how well that worked out.

Comic Books

 * The Beast Riders of Onderon from the Tales of the Jedi series. Though primarily used as mounts, the drexl beasts use their fangs and claws in battle.
 * Though not living creatures, the (original design of the) Basilisk war droids used as mobile battle platforms by the Mandalorians are in the style of large, animalistic mounts.
 * Kurt Busiek's Arrowsmith has a version of World War 1 fought with various fantasy creatures.

Film

 * The famba-mounted Shield Generators used by the Gungans in Star Wars Episode I.
 * In Three Hundred, the Persians used elephants as battle platforms and a rhinoceros as a juggernaut against the Spartans.
 * D-war was full of these, complete with 16th century rocket launchers that could take out Abrams and air support that attacked Apaches.
 * The Mûmakil ("oliphaunts") from the Lord of the Rings.
 * Don't forget the Wargs.
 * Dragons: in many films, from Dungeons & Dragons to Eragon, dragons are not evil flying monsters, but war-machines ridden by attacking forces.

Literature

 * In Poul Anderson's novel Operation Chaos, it's mentioned that the Allied forces utilized basilisks as war machines during World War II. Also dragons (the phrasing leaves it uncertain whether they're flying dragons or the equivalent of tanks) and, in the Navy, krakens for an amphibious assault.
 * Dragons in the Temeraire series are a major part of every military force in the world, and act as something rather like an Air Force. In addition to fighting each other claw-to-claw, they're used to drop bombs and the like, and breeds with breath weapons like fire or acid are especially valued for their destructive ability.
 * The Marat in the Codex Alera treat their Bond Creatures this way, thanks to their Proud Warrior Race Guy culture. It's bad enough to have a horde of screaming barbarian warriors charging you, but a horde of screaming barbarian warriors with terror birds and dire wolves or riding giant ground sloths is another matter entirely.
 * Scott Westerfeld's series Leviathan have the Darwinists who use fabricated beasts not only in battle as well as in everyday life. See: The Leviathan,  and Russia's War Bears.
 * In the Known Space novel Destiny's Forge, the evil Kzinti use bio-monsters called rapsari as well as soldiers, including some designed to operate ballistae or dissolve their way through blast doors.
 * The Windup Girl by Paolo Bacigalupi. War megadonts (giant genetically-engineered elephants) have carbon fibre armour, blades attached to their tusks and machine-gun cages on their backs.
 * John Ringo's March Upcountry series features reptilian creatures used much in the manner of elephants. Though they're reptilian, they have the temperament of cows. Well, most of them do. One of them is quite aggressive. Also, Prince Roger has a pet Dogzard who is fiercely loyal and more than happy to eat Roger's enemies.
 * Tad Williams's The War of the Flowers features dragons. To give a sense of scale, he was tempted to remove the scene in which they initially appear due to its similarity to an event that occurred during writing; the 9-11 terror attacks.
 * In Harry Turtledove's "Opening of the World" trilogy, the main characters, and everyone on their side, were stunned to discover that the invading "Rulers" rode mammoths into battle. Herding mammoths was one thing, but no one had ever imagined riding them. The Rulers also rode deer which they'd trained to jab enemies with their antlers.
 * Turtledove's Darkness Series used dragons as the air force, whale-like leviathans as submarines, and behemoths -- drawn on the covers as elephant-sized, shaggy rhinos -- as tanks and self-propelled artillery.
 * The Animorphs are the battle beasts themselves when in morph.

Real Life

 * Many historical armies used elephants in battle. Also horses weren't always just mounts- remember that kick.
 * They also were trained to kicked with their front legs, rather than rear. They were also trained to bite enemies: knights' steeds had to be fitted with iron muzzles when not in battle.
 * See the Lipizzaner Stallions' "airs above the ground". Those cool tricks were originally developed for use in battle.
 * The elephants were also trained to be more than passive on the battlefield. Aside from the obvious trampling and flinging of enemy soldiers, as well as carrying archers and spear men on their backs, some elephants were taught more horrific techniques. The Mughals for example taught their war elephants to take an enemy combatant, pin one of his legs to the ground with the elephant's foot, grab hold of the other leg with the trunk, and pull in two different directions, to disturbing effect. Its certainly slower than simply trampling the man to death, but the psychological effect more than made up for this.
 * The cliche that elephants are afraid of mice come from the time of the Punic Wars; according to folklore, Romans learned that the Carthaginian war elephants were confused by, and became scared of, things that were smaller than them and moved quickly and erratically. Thus, they began to deploy hordes of mice on the battlefield to render the war elephants useless.
 * Dogs: Romans used dogs for war, while Germans were famous for it. Even after WWII, war-dogs would have to be gassed, or else they would continue attacking and killing people as they were trained to do.
 * War dogs were a more decisive force on the battlefield than horses in some parts of the Spanish conquest of the Americas.
 * A darker side is the use of animals as disposable explosive delivery systems, such as anti-tank dogs and bat bombs.
 * That's just the tip of the iceberg. There have been such things as exploding rats, nuclear depth charge armed killer whales, incendiary monkeys, attempts to develop pigeon guided missiles, and the horribly misguided effort to use cats to guide munitions onto ships (under the logic the cat would prefer to land on the dry boat rather than the water around it). Of course, humans have also been used for all of these purposes, so yeah...
 * In The War On Terror, donkeys have been used by insurgent forces as bombers.
 * The Romans also used pigs as a weapon of war. Smear a pig's backside with tar, roll it in straw, set the straw on fire, and watch as a squealing ball of flame charges and scares the crap out of ANYTHING on the other side.
 * The historical accuracy of the use of flaming pigs is in question. Normal war pigs however are said to have been used to counter war elephants (they supposedly frightened them).
 * Large, strong, fast, fairly intelligent, aggressive... don't mess with pigs.

Tabletop Games

 * Warhammer has several of these: Dark Elf Hydras, Ogre Rhinoxen Scraplaunchers, Skaven Giant Rats, Goblin Cave Squigs, And Lizardman Salamanders and Stegadons.
 * Warhammer 40000 keeps the tradition alive with Ork Squiggoths and Kroot Knarlocs.
 * And all the larger Tyranid units.
 * One of the main differences between HORDES and WARMACHINE is that the forces in the former game utilize various creatures instead of the Mechanical Monsters of the latter.

Video Games

 * Hunters in World of Warcraft can tame nearly any beast. If it is a 'beast', you can tame it and use it in battle. Anything from a Turtle, to a Lion, to a Wolf, to even a moth can be used as a pet in battle. Beast-Master specialized hunters can tame even special pets such as T-Rexes (They shrink to a fraction of their original size on being tamed).
 * The Golden Axe series was famous for adding mounts to the action, from fire-breathing dragons to giant scorpions and those weird little parrot-beaked lizard things from Altered Beast that whipped with their tails.
 * War Craft II has the Dragons enslaved by the Horde.
 * III has the Kodo Beasts used by the Horde, which carry huge drums into battle and can eat enemies. Also the Chimerae, Hippogryphs and Faerie Dragons used by the Night Elves, as well as the Frost Wyrm (skeletal dragon) used by the Undead. In Frozen Throne, the Naga use a variety of non-sapient creatures to swell their ranks including Mur'guls (cannon fodder), Snap Dragons (ranged fire support) and Couatls (air support).
 * Dragon Force gave a number of it's Ninja generals a frog-mounted cannon they could use to attack enemy generals.
 * The Locust Horde in Gears of War are pros at adapting the underground fauna for battle purposes.
 * Bloodmounts: Exactly What It Says On the Tin, a Horse of a Different Color that Beast Rider Locusts ride on while shooting at you. They also possess a mean bite themselves.
 * Reavers: Large, flying squid-like beasts. Usually affixed with mounted guns. Skorge has his own personal Reaver called the Hydra which is somewhat larger than average.
 * Seeders: Towering insect-like creatures. Used as artillery/mortar launchers by firing Nemacysts out of their thoraxes.
 * Nemacyst: Sort of like a mini-Reaver. Leaves a trail of ink as it flies through the air. Used effectively both as ammunition and to block out communications by covering the sky in ink. Baby Nemacysts are used as ink grenades.
 * Corpsers: Giant, spider-like digging creatures used to make Emergence Holes for Locust ground troops to funnel out of.
 * Riftworm: A GIANT WORM! that appears in Gears of War 2. There is only one, and the Locusts used it to sink entire cities. Then you kill it from the inside.
 * Brumaks: Big honkin' dinosaur-like things with chainguns and rocket launchers strapped to them. Basically the Locust's tanks.
 * Leviathans: Giant fish-like monsters that live underwater. May not be tamed by the Locusts as they chuckle and retreat when you get close to their lairs. Anvil Gate confirms that there are more than one, and that they can go Lambent.
 * Siege Beasts: Huge grasshopper-like creatures in Gears of War 3 strapped to a device that uses their powerful hind legs like a catapult.
 * Gas Barges: Giant blimp-like puffer fish with gondolas attached underneath. Used for transportation.
 * Background information from The Elder Scrolls games lists a variety of different types of Khajiit, or cat-people, including the Senche-raht tigers, 12-foot tall sentient battle-mounts that weigh upwards of four tons.
 * In the backstory of the Geneforge series, the Shapers used their ability to create and alter life to conquer the world. Creations commonly used in battle by the Shapers include kyshakks (think of a stegosaurus that spits lightning), battle alphas (humanoid, but big, strong, and very tough), and glaahks (Armless Biped with a paralytic sting).
 * In Pokémon Red and Blue, Lt. Surge mentions how his Pokemon saved his life during a war.
 * In Dragon Age: Origins, Fereldens use mabari hounds as war dogs. Originally bred by a mage, they are incredibly strong and intellegient. As one solider puts it, a well-trained "mabari hound" is as dangerous as any sword. You can recruit one of these massive dogs into your party.
 * The darkspawn themselves use "ghouls" — creatures that have been corrupted by the darkspawn taint — as beasts of battle. The most popular of these are wolves, bereskarn (corrupted bears), corrupted spiders and dragons.
 * The Force-sensitives Felucians at The Force Unleashed used Rancors as war beasts against Galen Marek and the Imperial forces who attacked their homeplanet Felucia. The rancors were still nothing compared with Marek, who usually curb stomped every one of them. Not even the Bull rancor, the alpha male of Felucia's rancor community, could defeat him.
 * Command and Conquer show-cased explosive cows so often that by the time the game was released it was an expected tactic.
 * The Red Alert sub-series featured attack dogs (one bite kill against infantry) and dolphins armed with sonic weaponry. In the third game, the Soviets start fielding tamed bears instead of dogs.
 * the Tiberian Sun manual mentioned that the Forgotten have managed to tame tiberium fiends to use as guard dogs. This comes into gameplay as well; in any map where Umagon is a playable character, having her approach a fiend will automatically recruit it as a playable unit.
 * The Total War series, being based on Real Life (mostly), features warhounds, incendiary pigs, and elephants, including elephants covered in armor and elephants with freaking cannons mounted on them.
 * Para World is built around this trope. In a World where dinosaurs stroll through villages, and no one sees it as weird, someone is bound to have come up with the idea of using them as mounts. From regular wagon-pulling reptiles to massive armored Titan-class T. rex, seismosaurus, and triceratops used as ultimate war machines. The Norsemen, living in colder climates, tend to use mammals such as sabertooths and mammoths, although they do use a few dinosaurs such as their triceratops titan. They also have Steampunk technology, allowing them to field steam tanks and ironclads. The Dustriders (Bedouin-like nomads) are the faction that tends to use the dinos the most, given their low technological level. The Dragon Clan (an East Asian isolationist culture) has gunpowder and Bamboo Technology which they mostly use for traps.
 * Due to the mechanics of the game, the different units from the three factions hardly differ aside from cosmetic differences. For example, a Norse steam tank is about as powerful as a dinosaur with a catapult on its back.
 * Legacy of Kain: Soul Reaver 2 has armored war dogs.
 * Aztec Wars has one or two of these for every nation. The Aztecs have big cats and spy eagles, the Russians have war bears, the Chinese use yetis and War Elephants. They are available after specifically building a nest, a cave or a stable in your base.

Western Animation

 * The series Dino Riders, where humans and aliens fought each other using Dinosaurs strapped with missiles and Frickin Laser Beams. Think Zoids without the mecha.
 * The Fire Nation's Komodo-Rhinos in Avatar: The Last Airbender. During the Siege of the Northern Water Tribe, a number of them are shown with small catapults strapped to their sides as mobile artillery.
 * Adventure Time has the ANCIENT PSYCHIC TANDEM WAR-ELEPHANT.
 * He-Man and Skeletor had Battle Cat and Panthor respectively.