Villain Overview
You took everything from me when you sent Abigail into that machine. Now I'm taking everything away from you.
~ Yokai preparing to destroy Krei Tech and kill Krei for revenge.

Professor Robert Callaghan, or also better known by his supervillain name Yokai, is the main antagonist of Disney's 54th full-length animated feature film Big Hero 6, and a minor character in Big Hero 6: The Series. He is a former university teacher presumed dead in a fire; until he later re-emerged using a vast army of microbots in his plan to take revenge on Alistair Krei, whom he blames for the supposed death of his daughter Abigail Callaghan. He is Hiro and Baymax's arch-nemesis.

He was voiced by James Cromwell, who also played Joseph Campbell in The General's Daughter, The Colonel in DreamWorks' Spirit: Stallion of the Cimarron, Warden Hazen in the 2005 remake of The Longest Yard, Captain Dudley Liam Smith in L.A. Confidential, Dr. Arthur Arden in American Horror Story: Asylum, and William Donahue in Eraser.


Big Hero 6

Professor Callaghan is a renowned roboticist in San Fransokyo, credited with the creation of Callaghan's Laws of Robotics. He first appears in Tadashi's university known as the San Fransokyo Institute of Technology, with Tadashi and his younger brother named Hiro. Upon introducing himself to Hiro, Callaghan speaks that Hiro's fighting robot employs his laws, and subtly reprimands him for bot-fighting as opposed to putting his intellect to use. It is this that motivates Hiro to join Tadashi's university and to invent the microbots. Hiro's subsequent demonstration of his new microbots in order to join the university visibly impresses Callaghan, as well as Alistair Krei.

Krei expresses great interest in buying Hiro's microbots, but Callaghan intervenes with Krei's offer and states his distrust of Krei, convincing Hiro not to sell his microbots (a subtle reference to his hate of Krei). Once Hiro denies to sell the microbots, Callaghan accepts Hiro into the university. After the presentation, a destructive fire breaks out in Tadashi's showcase with Callaghan still inside. Tadashi runs inside to save Callaghan, but the building explodes, killing Tadashi and leaving Callaghan to be presumed dead.

As Yokai, Callaghan is later found within a warehouse in a shadier part of San Fransokyo, where Hiro's microbots led him. Hiro and Baymax discover what appear to be robotic arms (highly resembling Callaghan's robotic arms in the showcase) manufacturing microbots by the dozen. Before Hiro could investigate any further, Yokai appears and bundles the microbots into a slithering wave, and attempts to kill Hiro and Baymax. Hiro catches a brief glimpse at the masked man before escaping out of a window. Hiro explains the matter to the local police station, but the cop he tries to explain the matter to is unsure whether to believe him or not, and Baymax's battery runs low, rendering his evidence almost completely unreliable.

Still devastated about the loss of his brother, Hiro theorizes that Yokai stole his microbots, then caused the fire in Tadashi's showcase to cover his theft. Determined not to let him escape, Hiro builds Baymax a suit and installs combat into his databases, as a chip of his design. Hiro tracks down Yokai near the warehouse. Hiro sees Yokai and ducks for cover and seeing the villain gathering massive parts from the nearby bay with the microbots. Suddenly, the rest of Tadashi's friends (GoGo TomagoHoney LemonWasabi, and Fred who Baymax had contacted earlier) drive in. Hiro desperately attempts to explain the situation, but Yokai sees them and attempts to crush them. Narrowly saved by Baymax, Hiro and the rest of the team drive off with Yokai right behind them. Yokai attempts to kill them by throwing vehicles and using his microbots as a wave to attack them. It ends with Gogo accidentally driving a car into the bay and sinking into the water. Yokai looks on, and, thinking they drowned, leaves.

Baymax saves Hiro and his friends by discarding his armour and using his buoyant balloon body to float them back up to the surface. They retreat to Fred's house, which, surprisingly, is a fancy mansion. Baymax then reveals that he scanned Yokai. Planning to do a mass scan on San Fransokyo to find out his identity, Hiro builds a new battle suit for Baymax, equipped with offensive capabilities and rocket-propelled flight, and designs suits for his friends, organizing the team known as Big Hero 6 to bring Yokai to justice. Baymax and Hiro fly above San Fransokyo and scan the city, and Yokai's information is matched to a distant and quarantined island.

Flying down to the island, the Big Hero 6 discover what appears to be a machine in progress. A video feed shows the construction of the machine, which was meant to be a massive teleportation device. Krei is seen in the feed, and a mortal accident accidentally ends up with the machine exploding while a test pilot named Abigail is launched inside as it does, leaving her to be presumed dead. This leaves Big Hero 6 to assume that Krei is the guy under the mask since the government forced him to shut down his experiment after Abigail's supposed death, and they believe Krei is using Hiro's microbots to steal his own machine back. Before the feed continues, however, Yokai suddenly appears, armed with the microbots, and yet again attempts to crush the heroes. Hiro and everyone else fights Yokai, ending with Hiro and Baymax flying into Yokai and knocking off his mask.

As they got up, Yokai turned and showed his true identity as Professor Robert Callaghan. Realizing that Callaghan was the one who caused the fire that killed Tadashi, a shocked Hiro confronts him for this, only for the professor to explain coldly that Hiro's microbots saved him and that he believes Tadashi's death as his own mistake. Out of complete rage, Hiro removes Baymax's healthcare chip and orders him to kill Callaghan. Baymax goes out of control and attempts to kill the now powerless Callaghan under Hiro's orders, but the other members try to stop him, allowing Callaghan to gather up the microbots and flee. Baymax is forcefully stopped and Callaghan reclaims his mask to use the microbots to escape, much to Hiro's rage.

Hiro is very angry at his friends for interfering and flies off with Baymax, leaving the others behind on the island (although Fred tells him that his butler picked them up and flew them back in his family's helicopter). After trying so many failed attempts to gain access to his access port, Baymax asks if killing Callaghan is what Tadashi would have wanted. With Hiro entering a fit of anger and despair, Baymax shows Hiro a video compilation of Tadashi making improvements, making Hiro regain his senses and realize that killing Callaghan will not do any good. Big Hero 6 regroups and looks over the video feed again. It visibly shows Callaghan furiously storming into the building, raging at a frightened Krei by telling him that he knew the portal "wasn't ready". The building was quarantined by the government, and Abigail the test pilot is revealed to be Abigail Callaghan, the professor's now supposedly dead daughter. It was then Big Hero 6 realized that Abigail's apparent death drove Callaghan to a point of vengeful anger, leading him to adopt the masked costume and manufacture the microbots to take revenge on Krei.

Big Hero 6 rushes over to Krei Tech's main building, where Krei is making a speech about the new building's opening. Callaghan, again as Yokai, suddenly intercepts, seizing Krei and dragging him into the air and directly confronting Krei about his daughter's supposed demise. Krei begs that Abigail's presumed death was an accident, but Callaghan dismisses his plea and accuses Krei and his arrogance and greed, and lack of regard for the consequences of his actions for being the cause of Abigail's death. He then tells Krei that he took everything from him when he sent Abigail into the portal and apparently disregarded her life and now he will take everything from him in retaliation. Callaghan takes the remains of the teleportation machine and with the microbots, rebuilds it over Krei Tech's building, intending to destroy it. He tells Krei that he will make him watch everything he built get destroyed, then he would kill Krei next.

Big Hero 6 arrives, and Hiro tries to reason with Callaghan to spare Krei, admitting that he understands his pain and knows the very feeling of loss. Realizing that what Hiro says may be true, Callaghan hesitates and appears to consider stopping his plan. However, when Krei cowardly pleads for mercy, the villain once again allows his disgust at Krei's lack of courage to consume him and instead opts to kill both Krei and the Big Hero 6, saying furiously that he wishes to have his daughter alive again, using the microbots to pin down each member of Big Hero 6. In a climactic final battle, Hiro has everyone work from different angles, succeeding in tricking Callaghan into sucking his microbots into the portal the machine above created.

Callaghan (without anymore working microbots) is about to receive a punch in the face by Baymax, but it turns out that the robot decides to spare the former professor. Baymax removes the mask and crushes it, rendering the remaining microbots useless. As such, Callaghan starts to fall along with the portal, only to be saved by Baymax and Hiro. Before Callaghan can be arrested, Baymax detects life within the teleportation machine's dimension, revealing that Abigail is alive but in hypersleep, much to Callaghan's surprise. Hiro and Baymax fly into the portal and successfully manage to draw Abigail out, but at the cost of Baymax's original body.

For his crimes, Callaghan is arrested by the police, but he manages to see Abigail one last time before being driven off in a police car, and his sad facial expression implies that he becomes remorseful for his actions as he waits to be given a life sentence in prison for his crimes.

Big Hero 6: The Series

Hiro.... I never thanked you for saving my Abigail. (Hiro: I'm.... I'm glad she's okay.) I never set out to hurt anyone... what happened to Tadashi... because of me. I know it's not enough... but I'm sorry.
~ Callaghan expressing his remorse for his actions.
Callaghan briefly appeared in the episode "Mini-Max", where Hiro paid a visit to him in his prison cell. It is revealed that Callaghan was a close friend of Professor Granville (who became the new dean following Callaghan's arrest), and that Hiro only came by to ask about what caused her to leave 20 years prior. Callaghan then confessed that there were rumors about an unsanctioned project going wrong that caused Granville to resign out of shame and that the incident was covered up by an "official" story of a pipe burst. Hiro later learned from Granville that a certain student named Bob Aken was responsible for the unsanctioned project and that he suffered injuries after the incident, which prompted Granville to resign out of guilt since she allowed him free rein in the lab at that time.

With this information, Hiro thanks Callaghan for his help, but before he could leave, Callaghan reminds that he is thankful towards Hiro for saving Abigail's life, and that he is truly sorry for Tadashi's death. Callaghan also admits that he understands that his apology is not enough for Hiro to forgive him, though Hiro assures one day that he will.


What makes Marvel villains interesting is that they are righteous. They think they are doing the right thing, or at least the necessary thing, which makes them more human and relatable. Yokai is not a villain in his own mind.
~ Tech supervisor Hank Driskill describing Yokai in The Art of Big Hero 6.
Professor Callaghan initially appears to be an authentic, enthusiastic, friendly and genial teacher befitting his appearance. He clearly looks for potential in his students and displays a qualitative measure of cunning manipulation in the means of subtly telling off Hiro for using his intellect in illegal bot-fighting. Callaghan is also an experimental, inventive, brilliant, and presumably revolutionary man, responsible for coining Callaghan's Laws of Robotics. He was presumably famed for these reasons, as Hiro was immediately starstruck upon learning who Callaghan was.

However, it was just a cover of his former self as behind this, Callaghan was tortured, ominous, brooding, treacherous and ruthlessly destructive. He was an immensely tragic figure motivated by the loss of his daughter due to Krei's reckless misuse of Project Silent Sparrow, leading to a bitterly and hatefully murderous resentment of Krei and a lust for vengeance. As Yokai, Callaghan was a resoundingly stoic, merciless and no-nonsense individual, who never said so much as a word in his attempts to kill Big Hero 6. He employed ambush as much as he did a brute force, and never let up in his assaults.

Callaghan had become a dark reflection of Hiro, an individual who was racked with grief over the loss of a loved one and thus sought revenge on the blameworthy wrongdoer. However, while Hiro eventually learned from his mistakes and accepted his loss, Callaghan's morals had been too thoroughly drowned, instead allowing his pain to consume him. He coldly dismissed Tadashi's death as his own mistake and ultimately rebuffed Hiro's pleas to accept his daughter's loss, despite showing a hint of regret. However, upon seeing his daughter alive and realizing all of his senseless destruction was ultimately for nothing, he became very upset for his actions, implying immense remorse. This was later shown in the series when he expressed this to Hiro, admitting that he was wrong to let Tadashi die and thanking Hiro for saving Abigail's life.

Ultimately, Callaghan was undeniably manipulative and ruthless, but in becoming so, he became one of Disney's most sympathetic and three-dimensional antagonists.


Yokai appears as a tall, shady man, dressed so that no skin shows. He wears a black suit outfitted with dark gloves and a white kabuki mask to conceal his face. He has white wrapping across his legs. He telepathically leads a vast army of "microbots", which he can bundle into several different forms, most notably as a swarm he can use to stand and ride on as a sort of wave.

As Callaghan, he appears as a middle-aged professor with gray, thinned hair, and blue eyes. He bears a rather striking resemblance to Rourke, the main antagonist of the 2001 animated Disney film, Atlantis: The Lost Empire, hinting at his true nature.

Powers and Abilities

Yokai's primary source of power was Hiro's microbots. With the transmitter created to gain control over the miniature robotic army, Yokai was able to transform the robots into a deadly force, capable of performing immensely dangerous acts. To control them, the headband of a transmitter was inserted into his kabuki mask, and without the said mask, control over his Microbots would cease, thus rendering him powerless. Though he generally lacks physical strength, Yokai has been shown to have a considerable amount of physical attributions, as seen during the car chase through the San Fransokyo streets. Even so, such attributes weren't utilized in other scenes, as he heavily relied on his Microbots and own, personal cunning, to do away with his enemies.

The Microbots were capable of grouping together and forming into anything the mind could conceive. When in battle, Yokai's typical course of action would be to form the Microbots into constructs of various shapes and forms such as spears/spikes that would be used to impale his enemies and fist-like blocks which would inflict devastating blows with powerful force capable of breaking solid concrete and knocking back armored foes such as Baymax. He would also use the strength of the Microbots to utilize surrounding objects heavy in weight to crush his enemies, such as a cargo container, a car, or a massive piece of concrete. Yokai also uses their durable forms to block most incoming attacks that were meant to incapacitate or harm him, such as the flames from Fred's monster suit.

The Microbots could also be used as Yokai's source of transportation on multiple terrains, as they were capable of being used on both solid land and sea. During travel, Yokai would usually stand at the high center of the Microbots, which would be formed into a mountainous form during such occasions. Due to their high speeds and agile movement, Yokai can use the Microbots to catch up to and outrace cars in high-speed chases, scale and climb any surface, and dodge incoming attacks, all with great ease.

It should also be noted that Yokai's secondary source of power was his own intellect. With such power over the mind, Yokai was able to carry out his plot to solely rebuild Krei's portal (which is an example of his vast intelligence, in and of itself), steal Hiro's Microbots, and duplicate said inventions without having law enforcement caught on. In fact, if it were not for the unintentional interference of Baymax, Tadashi's healthcare robot, Yokai's plot would have very well succeeded.


Burning the midnight oil, Mr. Hamada?
~ Callaghan's introduction.
You must be Hiro. Bot fighter, right? When my daughter was younger, That's all she wanted to do.
~ Callaghan meeting Hiro.
Here we push the boundaries of robotics.
~ Callaghan gives some friendly advice to Hiro.
Nice to meet you, Hiro. Good luck with the bot fights.
~ Callaghan wishing Hiro good luck in the bot fights.
I wouldn't trust Krei Tech with your microbots.
~ Callaghan not trusting Krei.
Hiro: Professor Callaghan? The explosion. You died.
Callaghan: No. I used your microbots.
Hiro: But Tadashi. You let him die.
Callaghan: Give me the mask, Hiro!
Hiro: He went in there to save you!
Callaghan: That was his mistake!
~ Callaghan reveals his true nature when explained how survived and tells Hiro that Tadashi was to blame for trying to save him.
Callaghan: Setback?! Was my daughter a setback?!
Krei: Callaghan. Your daughter... that was an accident.
Callaghan: No! You knew it was unsafe! My daughter is gone because of your arrogance.
Krei: What are you doing?
Callaghan: You took everything from me when you sent Abigail into that machine. Now, I'm taking everything away from YOU!
Krei: No, no, you can't!
Callaghan: You're going to watch everything you built disappear, then it's your turn.
~ Yokai preparing to destroy Krei Tech and kill Krei for revenge.
Abigail is gone!
~ Callaghan refusing to deny Hiro's advice for Abigail's true wants.
I want my daughter back!
~ Callaghan wanting his daughter back before going on a rampage.
Callaghan: This ends now!
Hiro: Looks like you're out of microbots.
Callaghan: What?
~ Callaghan about to finish Hiro and Baymax before he could realize he's out of microbots.
~ Callaghan realizing that Abigail is still alive.


  • He is based on Lord Deathstrike from the original Big Hero 6 comic books. This would make him the first Disney villain to ever have roots from Marvel Comics.
  • His alias "Yokai" (妖怪) means "spirit" or "phantom" in Japanese.
  • Callaghan acts as a dark counterpart to Hiro. Both are brilliant inventors who end up suffering a tragic loss of a loved one (Tadashi for Hiro and Abigail for Robert). However, while Hiro eventually learns to accept his loss and change before he can fall into darkness, Robert stubbornly refuses to accept Abigail's loss, having been pushed too far into corruption to change.
    • However, upon seeing his daughter still alive while being arrested, he seems to show some regret, hinting that he may change or die much more with honour than in disgrace while in prison. He shows this by telling Hiro that he regrets what happened to Tadashi outright stating that he understands if Hiro couldn't forgive him.
    • This serves as an example of what would Hiro had become if he'd still consuming the vengeance.
  • Though Tadashi's death was ultimately an accident, Yokai is one of the few Disney villains to permanently kill off a major character in their respective film. Regardless, while Tadashi running through the fire meant he put himself in danger, Yokai is still accountable since he was the one who set the fire in the first place.
  • In production, Callaghan was originally known as "Dr. Martin Lebur".
  • Among the scripts and concept arts of Yokai, some of them depicted Yokai with slightly different powers: Instead of using masses of microbots, he uses what appeared to be liquid living biomass.
  • Originally, Professor Callaghan/Yokai was going to put together a team of San Fransokyo's greatest criminals (including Mr. Yama and the Fujitas) but was changed to a solo act.
  • His alias Yokai was never mentioned directly in the film, as it only appears in the film's merchandising.
  • According to Baymax's scans, Yokai suffers from an acute stress disorder and an emotional instability.
  • Despite his cruelty in telling Hiro that Tadashi's death was his own mistake, he does appear to be correct in saying so, as Tadashi chose to run into the SFIT building by himself, thus resulting in his death. That said as he himself acknowledges, nothing excused his callous way of saying it.


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