The heroes are in the middle of their adventure to defeat the Big Bad, when they hit a roadblock. For some reason, they cannot take the next step required to defeat their primary enemy. At least not until they go out of their way to retrieve a MacGuffin which will allow them to resume their quest. And when they do so, they could meet this character.
The Villain of the Detour is an antagonist who owns something the heroes need in order to continue their adventure. One defining aspect of this character is that they are an antagonist, but they range from having minor relations to the Big Bad to none at all. When they're defeated, it is not considered a major blow to the primary antagonist, because this character is not an extension of their will. If it's a movie, this character might appear at the beginning or middle of the story. If it's an arc series, this character is not the primary antagonist of said arc, although a section of it can be devoted to them.
This character is an antagonist, but they might not be a true villain. They may oppose the hero simply because they've been tasked with guarding what the protagonist needs. Or maybe they just want to use it for their own selfish desires rather than straight-up villainous ones. In addition to this character possibly not being a villain, the story they're in might not have a Big Bad to speak of—or even an actual antagonist. The heroes may be trying to stop an abstract threat, which is not being manipulated by anyone. Or they could be looking for lost treasure. Whatever the case, the character's status as the only antagonist present doesn't necessarily make them the Big Bad.
What the heroes need from this character can vary. Maybe it's a key that unlocks the gates to Mordor. Or maybe it's a Legendary Weapon that can defeat the Big Bad. Or perhaps it's just a map leading to said weapon. But unless this character is confronted, the heroes will not be able to defeat their main adversary.
After the heroes get what they need from them, this character has the potential to become a reoccurring foe that needs to be dealt with. They might have their own Evil Plan that needs to be stopped. Or maybe they're trying to get revenge on the heroes for stealing their MacGuffin. But they are still at best a secondary antagonist. Although, if the main antagonist is thwarted, this character could take their place due to the resulting Evil Power Vacuum. If this does happen, then they graduate from this trope. There is also the possibility of this character becoming subordinate to the Big Bad after his initial defeat, to which he would no longer be considered a side villain or in line with this trope.
The Villain of the Detour is not a Filler Villain, because the heroes can't progress unless whatever this character has is claimed by them. This character is also not the Big Bad Duumvirate, due to not being a villain the protagonists are primarily tasked with beating. And while this character can be a Lone Wolf Boss, they differ from that trope by always being mandatory to confront, instead of possibly being part of an optional mission.
Compare MacGuffin Guardian, Monster of the Week, Villain of Another Story. Compare and contrast Disc-One Final Boss, who appears to be the main antagonist but is later revealed to be a detour villain.
Examples
- Slayers NEXT: Lina and her friends are searching for an edition of the Claire Bible Manuscript, in which they run into at least one foe un-associated with Gavv who owns what they believe to be a copy.
- Moana: Before restoring the heart of Te Fiti, Moana and Maui have to take a detour to retrieve Maui's fishhook, the source of his powers. The hook is in the lair of Tamatoa, an egotistical treasure-hoarding Giant Enemy Crab. The heroes have to outwit him (and endure his Villain Song) before they can escape with the hook and continue their adventure.
- The Batman (2022): Despite being a big canonical villain, The Penguin here is an intermediary step for Batman to get through to the Riddler's plans.
- Conan the Destroyer has two of them: the wizard Toth Amon (who guards the diamond that's the key to the Horn of Dagoth) and the wizard who leads the guardians of the Horn themselves. They're not allied to the Big Bad, Queen Taramis, since she sends Conan & co on The Quest to retrieve the Horn, though they don't know what she's up to until far into the quest.
- Brytag in Red Sonja. He and his army keep the gate to a valley Sonja needs to cross in order to get to the kingdom of Queen Gedren. Brytag won't let her pass unless she pays or... does him a "favor", so she opts to kill him, take the key to the gate from his corpse and confront his army. Luckily, Kalidor shows up to help when she's surrounded.
- The Hitchhiker's Guide to the Galaxy (2005) has two. Humma Kavula (John Malkovich's character) and the poetry-reading bureaucrats. The band of heroes has to get through them before the final act villain reveal.
- Killa Harkan in John Wick: Chapter 4. He's connected to the High Table, but ultimately has nothing to do with the Marquis and his plans. But John has to kill Killa in order for his old association to sponsor his Duel to the Death with Marquis.
- The Merovingian in The Matrix Reloaded, who imprisons the Keymaker and is not subordinate to Smith or any other agent.
- Blackbeard, the Big Bad of Pirates of the Caribbean: On Stranger Tides, is searching for the Fountain of Youth. Jack Sparrow and Hector Barbossa must also confront a separate foe known as the Spaniard, because he and his army of soldiers have taken the chalices required for the Fountain of Youth to work.
- Return of the Jedi: Jabba the Hutt. His crime ring is not an extension of the Galactic Empire, but Luke Skywalker and his friends confront him to rescue their friend Han Solo.
- Thor: Ragnarok's Big Bad is Hela, played by Cate Blanchett, but the movie spends a good chunk of its runtime — and some of its most memorable scenes — with Thor and the Hulk trying to escape from the gladiatorial pits of The Grand Master, an unrelated villain played by Jeff Goldblum who has no particular ties to the situation with Hela and vanishes from the narrative as soon as Thor gets back to Asgard, apart from The Stinger showing him defeated.
- Subverted in Furies of Calderon, the first Codex Alera novel. In order to defeat the Marat warlord Atsurak, who is threatening the Calderon Valley, Tavi has to win the loyalty of Doroga, another Marat chieftain. To do so, he has to retrieve a mushroom with miraculous healing properties from the Wax Forest and in the process accidentally wakes up and confronts a monstrous creature that appears to be the Forest's guardian. Said creature, while powerful, never appears again after Tavi escapes from it... in the first book, at least. It's actually the Vord Queen, the ultimate Big Bad of the whole series, and Tavi accidentally woke her from hibernation prematurely, but nobody realized it at the time.
- Power Rangers Lost Galaxy starts out with Scorpius as the Big Bad, then it shifts to his daughter Trakeena. Then when the Power Rangers end up in the Lost Galaxy, a new villain, Captain Mutiny (a living pirate ship monster who is also a space pirate whose "ship" is a castle riding on a dinosaur) is the temporary Big Bad until they get out only for Trakeena to have Dropped a Bridge on Him as soon as he follows behind. He at first pretends to want to help, offering a box that will supposedly help them get home, but when they go to investigate and Karone notices he has slaves digging for gemstnoes, they realize he's up to no good. They all overhear Mutiny talking about a monster called Grunchor and try to get back in time to stop Mike from opening the box. They're too late but they do defeat Grunchor (albeit using a special attack that requires all the Megazords operating in unison) and Captain Mutiny remains the primary antagonist until they can escape the Lost Galaxy. In fact, one plot point is that they have to free all of Mutiny's slaves before they can leave.
- Kid Icarus: Uprising: Two non-villainous examples.
- The Chariot Master who challenges Pit to a combat race. He has no connection to any of the actual villains in the game, but Pit must beat him to gain control of his chariot.
- Dyntos, who created both the Three Sacred Treasures and the Great Sacred Treasure. He refuses to hand over the latter unless Pit can pass his challenges and even then demands Pit defeat the Treasure itself to prove himself worthy.
- Knights of the Old Republic:
- On Taris, the party has to steal the Ebon Hawk from Davik Kang—a crime lord who has no affiliation with Darth Malak—to leave the planet.
- The player has to kill a Krayt Dragon on Tatooine in order to obtain the Star Map that it's guarding.
- A giant firaxan shark called the Progenitor is guarding the Star Map on Manaan, and the player has to either poison it or destroy the kolto harvesting machine to let the shark grant passage to the map.
- Paper Mario:
- A few bosses in Paper Mario: The Thousand-Year Door have no connection to the X-Nauts or the Shadow Queen, but Mario has to beat them to acquire their Crystal Stars.
- Macho Grubba has the Gold Star, and he was using it to sap strength from younger fighters to keep himself fit.
- Before Doopliss gets recruited by Beldam, Mario fights him to get the Ruby Star.
- Cortez, a ghost skeleton pirate, is in possession of the Sapphire Star. After his defeat, he gives Mario the star and becomes friends with him.
- Many of those guarding the Pure Hearts in Super Paper Mario are not subservient to Count Bleck, a notable example being Francis, a nerdy chameleon who captures your guide Tippi—who unknowingly has the next Pure Heart inside of her.
- A few bosses in Paper Mario: The Thousand-Year Door have no connection to the X-Nauts or the Shadow Queen, but Mario has to beat them to acquire their Crystal Stars.
- While Emperor Percival Tachyon, a despotic tyrant that rules the Polaris Galaxy and intends to kill Ratchet and bring back the Cragmites using the Lombax secret, is the Big Bad of Ratchet & Clank Future: Tools of Destruction, Ratchet and Clank routinely wind up butting heads with Captain Slag and his band of robot pirates, either because they have something they need (like the IRIS supercomputer, a device that tells them where the Lombax Secret is located) or are trying to attack and board their ship on their way to a specific planet.
- Shantae: Half-Genie Hero: Shantae is forced to take a break from her adventure to gather parts for her uncle's latest invention in order to stop Holly, who has stolen everyone's memories. Holly, and the monster you fight in her place, Wilbur, have almost no baring on the plot beyond being Shantae's replacement as guardian genie. Holly later repeats her role in the DLC modes.
- Super Mario RPG: Neither Booster nor Valentina have anything to do with the Smithy Gang but serve as the Arc Villains of their respective portions of the game.
- Vampire: The Masquerade - Bloodlines: The Starter Villain is a small-time gangster who was supposed to sell an explosive device for the fledgling vampire Player Character's first mission, but double-crossed and beat up the fledgling's contact instead. He has no idea about the Masquerade and is entirely out of his depth when the fledgling shows up to settle the score.
- In The Order of the Stick, the need to find Girard's illusion-protected gate brings the heroes to the Empire of Blood, and at odds with its ruler, General Tarquin. Despite being Elan's father and having high aspirations as the Evil Is Cool main antagonist in his son's heroic legend, him and his entire arc have absolutely no relevance to the greater plot... to his dismay.
- RWBY has some large Grimm act as detour villains for the heroes to overcome, usually during travel. Examples include the Fei Long and Nuckelavee in Volume 4, the Lancer Wasps in Volume 5, and the Sphinx and the Apathy in Volume 6. Some humans also serve as roadblock antagonists, such as members of Raven's tribe (Though not Raven herself) in Volume 5, and, most notably, Cordovin and Adam in Volume 6.
- Avatar: The Last Airbender:
- Aang and his friends make an enemy out of Wan Shi Tong when they use his library to gain an edge over the Fire Nation after he told them not to abuse its knowledge.
- While Team Avatar was planning on going to Ba Sing Se regardless, Long Feng and the Dai Li become threats the Gaang are forced to overcome before they can accomplish anything in the city. And even worse, the Dai Li manage to keep the heroes occupied just long enough for the actual Arc Villain to sneak into the city.
- Harley Quinn (2019): Harley's crew is taking down the Injustice Leage, and Mr. Freeze is the next target on their list. In order to breach his lair, they must first acquire Firefly's flamethrower, which is being guarded by the unrelated villain Dr. Trap.
