Our brave hero has outsmarted the guards, sneaked into the ancient and mysterious crypt and now is about to lay his hands on the object of his long quest and/or about to open the grim-looking gate leading to said object.
This happens really often, with any kind of possible keeper. Monsters, Living Statues, Dragons or Demons summoned by portals and runes. It can be tracked back in old myths where a monstrous guardian keeps a treasure or a person, usually for his master. Of course, it doesn't need to be revealed in that exact way to qualify, but has just to be a monster keeping a treasure.
Usually the monstrous/inhuman nature of the keeper is justified by its skills: monsters tend to be stronger and more resilient, with hard skin or maybe Combat Tentacles or enhaced senses or Breath Weapon or whatnot.
A combination found so often it is its own subtrope is a dragon guarding a treasure hoard.
Sometimes overlap with Teleporting Keycard Squad, especially if the room appeared totally bare just a moment ago. See also Forgot to Feed the Monster when the spooky guardian is here... and already dead or incapacitated.
Compare Gate Guardian.
- Jidanbo from Bleach may count, if you wish to include overgrown humans.
- In Yaiba, Onimaru's Fortress is guarded by the Four Evil Kings, four demonic monsters acting as keepers.
- Mobile Suit Gundam AGE has a mechanical variant in SID, an unmanned, AI-controlled mobile armor that guards the EXA-DB. And since it uses weapons taken from the EXA-DB, its weaponry and defenses are decades, if not centuries, ahead of anything anyone else possesses.
- In InuYasha there are several examples, including Gozu and Mezu, the invincible guardians of the gate leading to the underworld, and a three-headed, fire-breathing wolf made of stone guarding the holy treasure of the Yoro Tribe, the Goraishi.
- In 3×3 Eyes, the gate to the Sanctuary in the Egyptian Kunlun is guarded by a small army of sand golems shaped as the Egyptian pantheon and a massive, Anubi-shaped Golem with petrification powers. Later, the Tomb of the Water General and the nexus of energy withing are protected by a mass of sentient, corrosive water. Though never stated, it is implied that the other four Generals' resting places are guarder by similar, elemental entities.
- The Transformers: Lost Light: Before the fall of Garrus-9, the Magnificence was placed inside Grimlock's chest, on the grounds it was the safest place in the universe. It took Scorponok a long time, and an incredible amount of torture, to get it out of Grimlock's chest.
- The Equestrian Wind Mage: Since the second season plays out more like a proper Zelda story than the first, Ganondorf places each of the Elements of Harmony under the protection of a powerful monster — the Element of Honesty is guarded by Grey Hoof and a Stallord, the Element of Kindness by Volvagia, the Element of Generosity by the Gohma Queen, the Element of Loyalty by Shanzom, and the Element of Laughter by Twinrova, while Ganon keeps the Element of Magic on his person.
- Shadows Awakening uses this a lot:
- The Chamber of Wishes, containing the Ring of Kur-Asan, is protected by a giant scorpion.
- The Hidden Shadowkhan Temple is guarded by an army of The Undead.
- The Unseen Enclave, where Solomon's Archive is located, is guarded by an efreet.
- The hidden Himalaya shrine where the Jewel was hidden is protected by yeti with ice powers.
- Queen of All Oni: The Sages guard the first tablet of the Teachings of Eternal Shadow, Nameless protects the second (on top of his duties as warden of the Vault of Endless Night), and the third is now only guarded by a single Old Master (the giant wolf that also protected it having succumbed to a Mutual Kill long ago).
- In The Ultimate Evil, unlike in canon, the Book of Ages has Guardian who Shendu and Valerie must outwit in order to access it.
- In the Pony POV Series, it turns out Moochick was this for the Rainbow of Light until he gave it to the Paradise Ponies and Megan, while Heathspike (Spike's ancient ancestor) was the guardian of the Rainbow of Darkness. Unfortunately, Heathspike dying in battle killing the evil dragon Smaug resulted in Lord Tirek getting his Rainbow thanks to a younger, far more apathetic Luna.
- The golden sword in The Man Who Saves the World is guarded by two golden living statues. Or, to be honest, two guys wearing golden suits.
- Plenty in the Lone Wolf series, especially during the quest for the Lorestones. They often act as Final Boss for a given book.
- Lord Haakon himself, and the monsters he summons, must be vanquished to retrieve the Book of the Magnakai at the end of book 5, Shadow on the Sand.
- The monstrous Dakomyd guards the first Lorestone in book 6, The Kingdoms of Terror.
- The Crocaryx and the Zadragon in book 9, The Cauldron of Fear.
- Book 20, The Curse of Naar, can be said to be mostly a series of MacGuffin Guardians, as several Demon Lords must be beaten to retrieve each time a new Plot Coupon.
- In Prester John Saga, several plot-relevant items are guarded by some monster. Book 1 alone has two pieces of the magical armor guarded by a massive octopus and a Hawk-man you have to trick or fight. At least two of them (one in Book 2, the other in Book 4) are also the Final Boss of the story.
- In Chronicles of the Emerged World, each elemental sanctuary has a sort of guardian. Subverted by some of them which aren't hostile at all and at least two which are guarded by a maze and enviromental hazards.
- Too many to count in Conan the Barbarian including the Thing in the Crypt, several Giant Snakes and at least one Giant Spider.
- Fablehaven has the cat-thing guarding one of the artifacts which has nine progressively more dangerous forms.
- In the first Gotrek & Felix book, there's a huge, Warpstone-mutated Troll guarding the treasure inside an abandoned dwarven tomb.
- In the Harry Potter series:
- Arachne in the third The Heroes of Olympus book, Mark of Athena.
- Classical Mythology has various guardian monsters like Ladon (the dragon that guarded the Apples of the Hesperides) and another dragon that guarded the Golden Fleece.
- In The Epic of Gilgamesh there's a fire-breathing giant Kumbawa who guards a forest of precious trees. Unlike other examples however, Gilgamesh's objective is the guardian himself, as he wishes to kill him for fame.
- In Egyptian Mythology the Book of Thoth is guarded by serpents and scorpions and a Serpent that cannot be slain, meaning it can come back together if its head is chopped off.
- Stormbringer supplement Demon Magic, adventure "The Velvet Circle''. The box the adventurers are seeking is guarded by a demon named Tyik Tyva. Inside the box is a Melnibonean Wheel worth 500,000 large bronze pieces.
- Battle for Wesnoth
- Spoofed to no end with the presence of a Giant Squid in a pool just outside the entrance of the Dwarven Kingdom is lampshaded. In a particular campaign said gag was brought Up to Eleven.
- Used more seriously in The Hammer of Thursagan where the tome needed to open the secrets gates in the final level is guarded by several vicious huge spiders.
- The Guardians of Temen-Ni Gru in Devil May Cry 3 may count. Most of them at least.
- In Final Fantasy II, each MacGuffin necessary for the plot advancement was guarded by a fearsome monster, including the Sergeant, Adamantoise and Shrieker.
- Grand Jewel, Polter Armor and The Last Kraken from The Legend of Dragoon.
- Onimusha has the huge hound Gertrude in the third game. The sequel features the gigantic, bug-looking keeper of Sawayama.
- Tobi from Ōkami. Unlike other examples, however, he must be defeated in a race.
- The second Rayman game has its share, including the Guardian of the Cavern of Bad Dreams.
- The huge Kraken in Tomb Raider: Underworld was probably left behind as a guardian.
- MARDEK: Chapter 3 features guardians in each of the elemental temples you visit. Fire had a wise, flaming dragonlike guardian named Girru who tests you by combat and finds you worthy, Water had a giant lobster-seahorse thing with a human rider, and Earth had the Rock Mole. Darkness was guarded by a wolflike alien mage called Solaar, but she had already been taken out by a villain when you get there and in fact joins your party in hopes of catching the thief.
- In God of War, Kratos must fight several Guardians during the course of the three games, including Pandora's Guardian, the Mole Cerberus and Skorpio.
- In EarthBound, each of the Sanctuaries is guarded by some sort of monster.
- In MOTHER 3, one of the needles is protected by the Barrier Trio, a group of posing, PSI-using golems.
- Pony Island: The three daemons: Azazel, Beelzebub and Asmodeus.
- The Order of the Stick:
- The outdated monsters guarding Dorukan's Talisman. Justified, since it's the Talisman itself which lured them there.
- The Black Dragon guarding the Starmetal fragment in the Wooden Forest.
- Kraagor's Gate is said to be protected by a bunch of monsters.
- Fangbone! has the titular Fangbone the Barbarian, and his friend from Earth, Bill. They're both tasked with guarding the big toe of Venomous Drool, making sure he never retrieves it to regain his full power.
- Magi-Nation has Snout & Peepers, a two headed hyren that lives in the Hall of Heros and protects the Book of Elders whenever it shows up there. Snout prefers to roast intruders on sight.
- The SpongeBob SquarePants episode, "The Lost Mattress" had Mr. Krabs' prized money-filled mattress guarded by a ferocious worm at the junkyard, after it got thrown away.
- Played for laughs in one Simpsons episode where the secret exit from the Nuclear Power Plant is guarded by a Giant Spider with a taste for human flesh.
- Grougaloragan's Dofus is guarded by a giant Stone Golem, able to switch its head (and power) for another if beheaded.
- Phaeris the Powerful, another dragon, is guarding Shinonome's dofus, thus forbidding any access to the Crimson Claws Island.
- In the special episode The Legend of Ogrest, a Giant Squid is guarding a pirates treasure and another Dofus .
- A rare heroic example is in Legends of Chima, where the lions guard the pool of chi that falls from Mount Cavora, and unlike most MacGuffin Guardians, are willing to share what they're guarding.
- In The Smurfs episode "The Enchanted Quill", the eponymous quill inside Castle Quill is guarded by griffins.