A frequent plotline in fiction is to have the characters go and retrieve a MacGuffin or Ancient Artifact, or locate a hidden valley, or something else that might have wealth or power or both. In the course of their travels, particularly if they're dealing with something that dates back to antiquity, they will run into, and most likely run afoul of, an organization dedicated to protecting whatever it is they're looking for, by any means necessary.
This is the Ancient Order of Protectors, an organization whose purpose can be defined as "keep this knowledge out of everyone else's hands no matter who they are". This usually means that the heroes will be forced to fight them one or more times along the way, since Poor Communication Kills, but this does not necessarily mean they are evil. Quite often, after misunderstandings have been cleared up, the heroes will team up with the Protectors to fight the Big Bad or work with them to prevent a global catastrophe.
The Protectors as a group are virtually unknown to the rest of the world, though they may form a secret society who lives among the average citizenry. They are not usually an Ancient Conspiracy, though it's not impossible that they are either, especially if they're trying to suppress all knowledge of whatever they're guarding. They do, however, usually have their own Ancient Tradition. They may or may not be an Organization with Unlimited Funding. There is some overlap with Secret-Keeper, though instead of just not telling anyone, they actively try to prevent people from finding out about it. They may not even know where it is themselves and think it's better that way.
Not to be confused with an Ancient Keeper, who is generally quite helpful... if you can get to him before these guys take you out.
Subtrope of The Order. Compare Impartial Purpose-Driven Faction, which they may fall into, and Threshold Guardians, though if the Order does its job right, no one will even get that far. Also see Masquerade Enforcer.
- Yu-Gi-Oh!: The Tombkeepers have been charged with guarding the secrets of the Pharaoh until his return, and guard some of the Millennium Items as well. Shadi is a much stronger embodiment of the trope, guarding the Pharaoh's Tomb for millennia and protecting it from robbers. He also tests people to see if they are worthy of possessing Millennium Items, and the tests are fatal if failed.
- The Grail in Preacher is the name of the secret organization which protects the bloodline of Christ, meaning they've been keeping the descendants of Jesus in cages and interbreeding them so as to keep the bloodline pure. They also secretly run the world: the Allfather reveals that every evening, the leaders of major countries are forced to call a secret number to contact him and say "Thank you", with those who refuse to humiliate themselves this way quickly replaced.
- An order of Greek priests established by the titular The Sandman (1989) guards his son Orpheus' immortal head. Not that anyone seems to be going out of their way to seek it these days, but they still take their job very seriously and are armed to the teeth, just in case.
- In Athena Voltaire, the Brotherhood of Shambalha was created to preserve the mysteries of the ancients (and specifically, to stop people finding or entering their city, Agharta). They were given certain supernatural powers to aid in this; one of these seems to be predicting the future and/or instant communication, since their members everywhere always know Athena's name even when they shouldn't.
- The Vassals of the Morning Star in American Vampire are an order of vampire hunters that for decades has protected the world from vampires. Its revealed that they have existed for far longer and used to fight against more than just vampires. More specifically, they were founded during the ancient Mesopotamian times to fight against an Eldritch Abomination that terrorized the world with its spawn. They were but were unable to destroy it since their leader became a Fallen Hero and turned into the Beast's protector, but they have kept it locked up for ages and only when the vampires emerged that they were reorganized to defend humanity against it.
- Battle for Terra: The Elders are a case this Hiding in Plain Sight, they are the leaders of their people, but they also suppress the development of new technology, and they keep their people from discovering the ancient war machines that nearly destroyed them centuries ago..
- In The Fifth Element, the Mondoshawan followers have hints of this; the first one seen was willing to kill an archaeologist who was getting close to finding the elemental weapon.
- In Indiana Jones and the Last Crusade, Indy encounters the Brotherhood of the Cruciform Sword, an ancient order dedicated to protecting the location of the Holy Grail. Following a traditional playing of the trope, they try to kill Indy (and Elsa the Femme Fatale Spy, whom he's with). He captures the leader, Kazim, and finds out what their purpose is; they realise that they both want to protect the Grail from the Nazis, and make peace. Later they attempt to prevent the Nazis' armed convoy from reaching the Grail's hiding place by ambushing it while it travels through a valley. They are brutally slaughtered. Indy finds one of them (apparently Kazim himself) and tugs at the collar of the shirt to reveal the cruciform sword tattoo. Indy doesn't say anything, but it's clear that he appreciates their sacrifice, or at least their intention.
- The Mummy has the Medjai, the descendants of the royal guards of Pharaoh Seti I who attempt to drive off any who might awaken Imhotep. Interestingly, while they know that the gods of Ancient Egypt are real, all the tribes of the Medjai have converted to Islam. And no, they were not invented for the movie; they're actually based on an Ancient Egyptian elite paramilitary police force of the same name.
- The reboot has Prodigium, a secret society based in the British Museum of Natural History, which hunts and contains monsters of all sorts around the world.
- Unusually, the How to Train Your Dragon trilogy centers around the founding of an ancient order. In Viking times, the village of Berk domesticated dragons, which up until then had been predators hunted by humans. Unfortunately, the concept of 'wildlife conservation' didn't really exist back then, so in order to protect dragons from warmongers and trophy hunters (like the one who almost drove Night Furies to extinction), the Berkians sent them back to live wild in the cavernous 'lost world' from which they originated. They settled an island nearby, vowing to keep the lost world hidden until humanity was ready to respect its inhabitants. Similarly, the dragons passed down respect for humans through the generations.
- The Magical Counsel of the Ancients in book 3 of the The Daring Do Adventure Collection.
- The Priory of Sion guards the Holy Grail in The Da Vinci Code.
- The Dresden Files has the Venatori. They fight to defend the world from ancient demonic gods called Old Ones ... by forgetting about them. By erasing every instance of the Old One's name and identity from mortal knowledge and then so forget themselves. With this done the Old One is banished to Oblivion, unable to return.
- The Empirium Trilogy: The Obex are a longstanding organization that protects, maintains, and studies the Gate. They aren't loyal to any particular kingdom or country.
- In the Foundation Series, the Second Foundation is a secret society charged with keeping watch over the First Foundation and correcting drifts in the Seldon Plan over the centuries.
- In the Nightshade Trilogy by Andrea Cremer, the Guardians (a group of wolf shapeshifters) have served their masters, the Keepers, for hundreds of years, and one of their most important duties is protecting some mysterious artifacts from their enemies, the Seekers. Turns out that the Keepers are really the bad guys and deal with dark magic, and the artifacts are actually pieces of a weapon that The Chosen One can wield to defeat them. The main character, a Guardian named Calla, eventually helps the Seekers steal them.
- Season 3 of Ash vs. Evil Dead introduces the Knights of Sumeria, an order of knights who have been fighting the Deadites for centuries.
- In MythQuest, there is an unnamed Chinese secret society that exists to prevent anyone from accidentally releasing Gorgos, a trickster god, from his stone and wreaking havoc on the mythology of the world.
- In Santa Clarita Diet, the Knights of Serbia is a group that has been looking for and fighting the undead like Sheila since the Middle Ages.
- In Tracker, Mel discovers that she's part of the Keepers of the Dark Secret, a bloodline of human/alien hybrids created in ancient times to prevent the alien super weapon that the show's Big Bad is after, from falling into the wrong hands.
- The Esoterrorists, the Ordo Veritas has a mandate to cover up and eliminate any instance of Outer Dark or Esoterrorist activity. The reason is that the membrane between our reality and the Outer Dark is weakened by belief in the supernatural and attempts to practice sorcery.
- Kingdom Death: The order of the Twilight Knights guard what precious little history humanity has managed to gather. White Speakers may also qualify.
- Dungeons & Dragons:
- In the Forgotten Realms campaign setting, the Harpers (also known as Those Who Harp) are a widespread, "semi-secret" organization whose agents are dedicated to fighting evil across the Realms, as well as preserving art and history and keeping a balance between civilization and nature. They have a somewhat notorious reputation as meddlers, particularly among those who question their definition of good. The organization has disbanded and reformed several times, and holds the fallen elven empire of Myth Drannor as the ideal, Shining City which they strive to recreate in the present.
- In Ravenloft, the Order of the Guardians are a monastic sect which keeps cursed artifacts sealed away in hidden locations, keeping them out of the hands of innocent bystanders and villains alike.
- The Sensei in older editions of Warhammer 40,000 were the (normally born, not lab-grown) sons of the Emperor, and the Illuminati a secret society devoted to protecting them from the Inquisition's attention.
- BIONICLE: The Order of Mata Nui had a few members guarding the Mask of Life on Voya Nui.
- The Guardians were native warriors who inhabited the jungles of Long Bay, Jamaica, in Assassin's Creed IV: Black Flag to prevent outsiders from accessing "the Observatory." Bartholomew Roberts mentions that they were apparently bred specifically to defend the site. Naturally, the player character has to fight his way through them to get to the Observatory.
- In a sacred temple on a forgotten planet, "high priests of a timeless religion" guard the hibernating battle-girl. A universe-threatening crisis is the only reason serious enough to wake her up. In this case, the protagonist is the one being protected.
- The Elder Scrolls series has the Blades. The Blades are an order charged with the protection and service of the Emperors of Tamriel throughout history. The Blades descend from the Akaviri Dragonguard, a group of ancient dragon hunters who were co-opted by Reman Cyrodiil, the Dragonborn founder of the Second Cyrodiilic Empire. (The Dragonguard considered those who are Dragonborn to be the ultimate dragon slayers, a trait adopted by the Blades.) In addition to serving the Reman emperors as bodyguards, the Dragonguard continued their mission of hunting dragons in Tamriel, driving them to apparent extinction. When the last of the Reman line was assassinated, the Dragonguard officially disbanded, but their members continued to covertly serve the Akaviri Potentates as spies and covert operators. When Tiber Septim, a new Dragonborn Emperor, rose to power, he officially reestablished the order which became known as the Blades. Over time, the Blades branched out into other areas including espionage and diplomacy. Indeed, while a select few were appointed by the Emperor to serve openly as diplomats or bodyguards, the majority of Blades agents acted covertly as couriers and spies. Following the demise of the Septim Dynasty, the Penitus Occulatus assumed guardianship of the Emperors, but the Blades continued to serve the Emperors as spies. When they realized the threat the Thalmor posed to Tamriel, particularly their intent to outlaw Talos worship, the Blades used their resources to resist the Thalmor throughout the continent. Without support, however, these efforts could not last forever, and in 4E 171, an Aldmeri ambassador delivered to Emperor Titus Mede II the severed heads of every Blades agent in Summerset and Valenwood, sparking the Great War. Devastated during the Great War, the Blades were then officially disbanded by the White-Gold Concordant. The survivors were forced underground to avoid the Thalmor, waiting for a new Dragonborn to emerge. Come Skyrim, one appears and the Blades rise once again.
- Starcraft II:
- A splinter sect of Protoss called the Tal'darim have appointed themselves guardians of the xel'naga artifact fragments Raynor is collecting during the main storyline, and violently try to keep them out of his hands. They turn out to be a subversion as they are actually working for the Big Bad Amon.
- Normal Protoss also have shades of this, they travel the cosmos studying and gathering relics of the xel'naga, and will keep them out of humans hands, but it's usually for a good reason (These Are Things Man Was Not Meant to Know, etc) and on other occasions they don't interfere with human archaeology.
- Fallout: The Brotherhood of Steel, full stop. They were originally a California-based military unit that went rogue after discovering that the government scientists under their care were performing inhumane Super Soldier experiments on "volunteers" that more often than not left the participants horribly mutated. After the bombs fell, they founded the Brotherhood in order to preserve old world technology and prevent dangerous tech from falling into the wrong hands. While a noble goal, they were ultimately indifferent to the goings-on in the Wasteland, preferring to remain politically neutral and stepping in only when events force their hand, such as when The Unity tried to forcibly turn all of humanity into Super Mutants (a horde of immortal, violent, orc-like monsters that ended up ravaging the wasteland for 210 years). In Fallout 2, the Brotherhood was well on its way to demilitarizing and becoming a simple research group when they got blindsided by the Enclave - technologically advanced remnants of the U.S government that were trying to kill everything and everyone, everywhere, forcing them take action or die. Ever since then, the Brotherhood has expanded their mandate to include aggressively destroying any advanced tech they think they can't control. One Brotherhood chapter was dispatched to the East Coast to recover tech - when they encountered post-war Pittsburgh and its thoroughly mutated and deranged inhabitants on the way, they exterminated most of the population and developed an ongoing hatred of all mutants that persisted into their occupation of the Capitol Wasteland. By Fallout 4, the Brotherhood has become the de facto governing body of the Capitol Wasteland, and launches a crusade into the Commonwealth of Massachusetts to defeat the Institute and eradicate its Synths, under the reasoning they are protecting the Commonwealth and the wider world from the threat of a second apocalypse caused by technology gone mad. By this point, they aren't interested in taking prisoners.
- World of Warcraft: Paladins seeking The Silver Hand learn of it from the Tyr's Guard, an ancient and secret order who have charged themselves with keeping the resting place of the Titan Tyr secure and hidden. The Legion's invasion renders their purpose moot, forcing them out of secrecy, assisting the Highlord in securing the artifact.
- In Mystery Case Files: The Countess, there was a knight order which only purpose was to guard the mirror in which the Shade was trapped and prevent this terrifying entity from being released at any cost. Unfortunately, this order disappeared at some point in history, leading lady Gloria Codington to find the mirror and become corrupted by the Shade.
- In this The Noob, Ohforf joins a guild. Upon learning their name, "The Righteous Protectors of the Crimson Star", he imagines them as this trope, but it turns out they're just a roleplaying guild with a Non-Indicative Name.
- Girl Genius: The Corbettites are a monastic order who both run a Europa-spanning railway system, and collect and store away dangerous Sparky artifacts in their catacombs.
- The US Department of Energy has considered different methods to protect nuclear waste repositories from trespassing in the far future, including an "atomic priesthood."