A character has a expert-level understanding of magical theory and applications — too bad they can't use the magic themselves.
While they can't use the magic of their expertise, they're the best one to explain its theory and how it works better than anyone. If you need to know the history of an artifact, the reason a spell works the way it does, or the favorite foods of a magical creature, this is the guy you come to.
They may act as Mission Control to less brainy mages, who can put all of this muggle's knowledge and theories into practice. As The Smart Guy of a team, they may also be the one to solve ancient mystical riddles and give play by plays of what magic is being used and why.
While many are content just to study and observe, some are really longing to actually practice. If the fates are kind, they may just be a late bloomer who eventually develops the skill. If the fates are less kind but they're still determined, they might be able to build some Magitek that functions mostly the same. While the applications of their inventions may be limited compared to The Archmage, it still allows them to climb pretty high up the Super Weight scale. Also, working twice as hard for half as much means they may discover a trick or two that conventional magic lacks the ingenuity to discover. It may be up to them to use their research and tools control magic run amok and kill dangerous creatures, or to restore the magic that has been lost to the ages.
Occasionally appears as a magic-user who was Brought Down to Normal by losing their powers; they didn't start as a muggle, but ended up that way without losing their knowledge. These ones often gravitate toward a Mentor role, because those who can't do, teach.
This type of character depends on a universe where Magic A Is Magic A.
The Muggle Born of Mages and the Mage Killer are often this. Downplayed examples can overlap with Inept Mage — the character doesn't need to be a literal Muggle. They just lack a useful level of magic compared to the Differently Powered Individuals around them. See also Fight Like A Normal.
- A Certain Magical Index: Index Librorum Prohibitorum has 103,000 magical grimoires committed to memory. She can survive this because she (allegedly) lacks the mana to cast any of the spells in them. This doesn't stop Index from disrupting or hijacking Sorcerer's spells.
- Mahou Sensei Negima!: Takahata grew up around experts in Functional Magic and Ki Attacks, but lacks the ability to use them himself. To make up for this he became a master of Kanka — the simple but difficult technique of connecting your body's mana and ki flows together to increase your physical abilities. True mages rarely bother with Kanka since while powerful it drains a lot of energy, and spells that enhance the user's strength are easier to learn.
- While she never personally studied magic, Kobayashi from Miss Kobayashi's Dragon Maid demonstrated herself to be a master of magical theory in chapter 65 when she got first place on a high ranking magic exam. This is due to the fact that the magic system is almost identical to the programming languages she uses at her job (the former having been used as the basis for the latter In-Universe).
- Nasuverse: Waver Velvet, later known as Lord El-Melloi II, is a magus who has excellent knowledge of magical theory but is incapable of all but the simplest spells (partly due to being a first-generation magus who lacks access to a family Magic Crest). In Fate/Zero, as a student, he still manages to find Caster's base before anyone else — by collecting water samples from around town and performing the mana equivalent of a litmus test. As an adult he's become one of the Clock Tower's most popular lecturers: while cranky, he's excellent at breaking down complex concepts so that they're easy to understand, and his background enables him to speak to students as equals.
- In the Advance Generation of the anime, May's brother Max is too young to be a trainer, but he studies Pokémon day and night, and is more knowledgeable about the Hoenn region and its creatures than anyone else on the team.
- Team Rocket's Meowth often keeps Jessie and James updated on Pokémon moves and types, and being one himself, can even translate what they say for them. Since he spent most of his life learning to be sapient, however, his own abilities as a Pokémon are limited, making him an ineffective battler most of the time.
- Ran To Haiiro No Sekai: Tamaso-sensei is a Muggle Born of Mages, but that doesn't stop her from being the leading expert on magic in the story.
- Prodigy from X-Men has the knowledge of every person he's ever met up to losing his mutation. This includes powerful sorcerers and mages. While he describes magic as too irrational to use, he manages to feint a spell that scares a universe devouring horror long enough to escape her.
- The Great Alicorn Hunt gives us Presto, who, despite born an Earth Pony (ironic, considering both his parents are a. Unicorns, and b. profs. of magic at the local university), is deeply fascinated with learning about and experimenting with magic. This, combined with his Eidetic Memory, means he's learned more about magic than most folks have forgotten about. What's more, he's figured out how to channel spells into crystals via his innate Earth Pony magic.
- In Eliezer Yudkowsky's Truth of the Sith, an alternate ending for Revenge of the Sith, Palpatine is revealed to actually be this. He studied ancient Dark Side practices all his life but cannot use them, hence why he was so determined to get Anakin to join him.
- In Star Wars, some people can be quite well-versed in matters relating to the Force despite not being sensitive to it themselves.
- Han Solo notably ends up like this by The Force Awakens despite his skepticism in the original trilogy. His mother-in-law Padmé Amidala in the prequel trilogy became similarly savvy after marrying a Jedi.
- Even though Chirrut Imwe from Rogue One has a jedi master-like understanding of the force, he can't use it the way a jedi can. Though he has learned to sense it, which comes useful in both defensive and offensive combat applications.
- Artemis Fowl: Artemis decodes a fairy's book to learn their language, and uses it to learn the limitations of their magic, and uses those limitations against them, despite not having any magic himself.
- Detective Steele, in the Daggers and Steele series of fantasy police procedural books, has a degree in the study of practical magic. She has no magic talent herself, but an early conceit of the series (more or less dropped in later books) is that she pretends to be a seer to get people to take her seriously despite being female in a male-dominated field. As it is, her understanding of the mechanics of magic frequently comes in handy when they have to investigate crimes involving magic.
- Dr. Abraham Van Helsing from Dracula is one of the essential examples of this trope in Gothic Horror literature. He is a Dutch Omnidisciplinary Scientist who is the first one to figure out the nature of Lucy's affliction (read: vampire attacks) and to devise effective treatments for it. Later on, he uses his knowledge to lead the Vampire Hunter team and employs hypnosis on Mina to exploit her connection to Count Dracula to track his movement.
- This is the function of "magicians" in the Enchanted Forest Chronicles. Whereas witches and wizards have an inborn connection to and use magic, magicians study it scientifically to try to understand it. The magician Telemain, a central character in the series, reminds us of this distinction at every opportunity.
- Jason Wood in Paradigms Lost. A data and image analyst, he has built a huge library magical and supernatural creatures from folklore and other sources, and makes use of that to both counter and communicate with them.
- In Jonathan Strange & Mr Norrell while true magic was a powerful force in the distant past, it seems to have gone away entirely and most "magicians" are actually this, guys who have their own private clubs and talk about what they've read but never been able to do. It comes as an enormous shock to society when two titular magicians, who can actually perform magic, come onto the stage. The book also contains something of an inversion, as there's a street magician named Vinculus who, unlike many other fake street magicians actually has the aptitude for magic, but absolutely no learning, and so he can never get his attempts at magic to work.
- Lord Darcy has Sir Thomas Leseaux, who has no magical ability, but is the world's leading expert in creating new spells due to his knowledge of magical theory.
- In Robert A. Heinlein's Magic, Inc. Archie isn't a magician himself but he runs a moderately successful construction business that employs a lot of them and he's pretty well aware of what they're capable of.
- In The Rithmatist, the main character, Joel, doesn't have the power to use Rithmatics (a form of chalk-line geometry-based magic), but is very passionate about the theory and strategy behind it. He gets the chance to study under a teacher of Rithmatics, and ultimately teams up with Melody, who has the power but isn't as skilled; they're able to effectively work together by having Melody trace the lines Joel draws.
- Vampirocracy: Leon doesn't literally have a degree (he was forced to drop out), but took college classes in Mythozoology, Thaumobiology, and Thaumodynamics. He understands how magic works, even if he doesn't or can't practice it himself. He's also part of the roughly 50% of humanity that can "feel" magic, and has deliberately cultivated this awareness. All this is important to his job as a supernatural PI and Monster Hunter.
- The Wheel of Time: The innkeeper Setalle Anan has knowledge of the One Power and Magical Accessories that's usually closely held by the Aes Sedai Magical Society. Subverted when she admits that she's a former Aes Sedai who lost her powers to a Magic Misfire.
- Nowhere Boys.
- Phoebe Hartley does not possess magical potential unlike the titular characters. However, she is so knowledgeable in magic and supernatural creatures, she is still able to act as The Mentor to them.
- The feature film reveals Felix's father, Ken Ferne, was once a magic user but was Brought Down to Normal after a depower event. But he still retains his immense knowledge of magic, having left behind clues for advanced spells (including a spell within a spell), to defeat the Big Bad.
- In Penny Dreadful, Vanessa and, to a much lesser degree, Ethan are the only good guys who have supernatural powers. Victor (Frankenstein—yes, that one), meanwhile, does the analytical and scientific work for the team, helping them untangle the villains' dark magics. He is also episodically helped by Ferdinand Lyle, who, as a linguist, helps them decipher ancient prophecies and incantations.
- On Supernatural, Hunters are Badass Normal who hunt monsters. Most have no magical abilities and compensate by relying on centuries of accumulated ant-monster lore to give them a fighting chance. Sam and Dean are often shown studying old journals, books or searching the Internet to figure out what type of monster they are fighting and what its weaknesses are. Bobby used to have an extensive library of lore books and was often consulted by other Hunters who faced an unusual monster.
- Jerry Russo from Wizards of Waverly Place is an unusual example in that he used to be a wizard, but gave up his powers to marry his mortal wife due to a law forbidding wizards from marrying mortals. He still knows everything about being a wizard, though, and is his children's primary teacher for magical subjects.
- Agent Fox Mulder of The X-Files seems versed in the mystical and arcane, including raising golems, voodoo curses, and dark magic blood sacrifices. He's paired with the science and medicine Agent Dana Scully. Together, They Fight Crime! that's tinged with weirdness.
- Ars Magica: People with no magical talent can train in the Magic Theory ability, although even the sourcebook warns that it's of minimal value to non-mages. It does, however, make them useful lab assistants for any mage who needs an Igor on hand.
- Blades in the Dark doesn't draw a particularly clear line between mysticism and hard science (since every weird bit in it is powered by electroplasm), so all player characters have some access to strange powers, which allows the dedicated Gadgeteer Genius playbook, Leech, to sub in for the dedicated weirdness archetype, the Whisper, through their faculties of observation and experimentation.
- In Burning Wheel, all magical skills are attainable for any character, but only those with Gifted trait can actually cast magic. For the rest, the skill use is merely academic.
- Dungeons & Dragons Edition 3.5:
- The "Use Magic Device" skill, normally found on Rogue-type classes, allows the user to ignore the requirements of magic items. This includes using a Magic Wand or scroll without having the ability to cast spells, or using a sword designed for elves without being an elf.
- On a more basic level, a character's ability to identify spells and magical effects depends not on their levels in spellcasting classes, but on their ranks in the Spellcraft skill. Any character can take ranks in Spellcraft, regardless of whether they have the ability to cast spells (though they may have to jump through a few hoops to add it to their class skills). Inversions are also possible, such as a Squishy Wizard who can identify thousands of martial arts techniques without being able to perform them.
- The Artificer class specializes in creating magic items and altering their effects. While they cannot cast spells themselves, they can replicate the effects of just about any spell in the game by "infusing" an object to turn it into a temporary wand keyed to that spell.
- In GURPS, in a Low or Normal Mana world only characters with the Magery advantage can cast spells. Because the standard magical system treats spells as skills like any other, it's entirely possible for characters without Magery to learn spells, even if they can't cast them. The Thaumatology skill represents a knowledge of the underlying structure of magic, and likewise does not require Magery or spellcasting ability.
- In Monster of the Week, the Expert is a person without special powers who has access to vast knowledge about the supernatural and history, as well as various rare materials for applying that knowledge.
- In early editions, a character without any magical ability could take the skill Magical Theory and understand how magic works. They could create new magic spells, design magic items, etc. — they just couldn't cast the spells or create the items. However, they could teach magicians how to do so.
- In 5th edition, one of the magic sourcebooks has a few runners briefly discussing this concept when one of them found out Mundane students were earning degrees in magical theory, and the stereotype was that only Awakened (that is, magic) students were earning these degrees. (In many cases, Initiating into higher levels of magic is performed as a thesis.)
- Also in 5th, while it's hard to impossible for mundanes to gather knowledge from first hand experience for how magic works, they are still able to learn a great deal from what other people have discovered and shared. Notably, the Arcana skill, which is the skill that associates with magical theory, is the only magic skill that doesn't actually require a Magic attribute.
- Dragon Age: In Origins, Dagna is a dwarf who wants to study at the Circle of Magi. Dwarves have absolutely no magical talent beyond rune crafting and enchanting, which is a slight problem. However, Dagna's analytical understanding of magical theory is so impressive that she's made breakthroughs that gained the recognition of archmages. She puts this to use, along with her background as a smith's daughter, to craft masterworks in Inquisition.
- Golden Sun: Kraden is an old researcher who understands alchemy, but isn't an adept himself. He travels along with the party, analyzing the lighthouse and making suggestions on how to solve the mysteries of alchemy and psynergy.
- Claus from Tales of Phantasia is a human scholar in a world where magic can only be used by those with elven blood. He gets around this by rediscovering a different type of magic that involves making pacts with spirits and binding them into magical rings.
- El Goonish Shive is a world where magic is a fundamental force of the universe, so that comes in handy when local Mad Scientist Tedd doesn't wanna just sit around being mission control next time danger comes around. Cue him building a power fist that stores the minuscule amount of magical energy he generates, and releases it all at once in battle mode. This gives him Black Eyes of Evil and lets him see an Eldritch Abomination's true form. Later subverted when Tedd is revealed to be a rare type of wizard called a Seer. He cant learn or cast spells naturally, but can learn how they work via Aura Vision and then create wands with the same effects that anyone can use, himself included.
- Most SCP Foundation personnel are basic humans who have to deal with supernatural/alien/eldritch/memetic/logic-defying anomalies on a monthly to daily basis. A lot of them die quite quickly, especially D-Class personnel, but those who survive long enough tend to accumulate a lot of knowledge of SCPs' properties and abilities, while usually developing no specific supernatural powers. Even doctors and professors who feature seriously anomalous properties themselves, most likely due to prolonged exposure to SCPs, rarely ever use direct powers. To contain or destroy dangerous SCPs, the foundation mostly relies on knowledge, other SCPs, planning, coordinated action, generous amounts of shooting if required (and efficient) and on-site nuclear warheads as a last-resort measure.
- The chi-wizard Uncle Chan and his apprentice Tohru from Jackie Chan Adventures. Both of them are human sorcerers who do not have any innate magical powers of their own, but they know how to channel magical energy (through using a dried-up dead lizard or blowfish as improvised magic wands).
- My Little Pony: Friendship Is Magic:
- Sunburst. While he is indeed a unicorn and can cast spells, his magic skills are on the level of common people. Yet, his knowledge is far greater, and he considers it an embarrassment that he can't actually use that knowledge. However, Sunburst saves the day in "The Crystalling - Part 2" with his magic knowledge — he identifies the exact combination of obscure spells needed to avert the wintery apocalypse, though he has to rely on others to cast them.
- Zecora, despite being a zebra, which functionally means she has no way to use magic like unicorn characters can, knows an incredible amount about magic. She knows enough to where she can function as Twilight's mentor on the subject, despite that she herself can't use any magic. On several occasions she's used her knowledge to either create potions for the ponies or to give them the information that leads to the episode's solution.
- Meadowbrook is an earth pony, and as such lacks the ability to cast spells or use active magic. However, much like Zecora, she's an accomplished herbologist and alchemist, and gained legendary status due to her ability to cure any ailment, magic or mundane, that she encountered. She's also evidently well-versed in unicorn magic, as shown when she's able to tell that a newly devised experimental spell would be able to work successfully after briefly reviewing its written form.