Yokai (Big Hero 6)

"I want my daughter back!"

- Callaghan to Krei "No! You knew it [the portal] was unsafe! My daughter is gone because of your arrogance."

- Callaghan confronting Krei "He was such a good man... What happened?"

- Honey Lemon talking about Yokai

Professor Robert Callaghan, also known by his supervillain name Yokai, is the main antagonist of Big Hero 6.

He is voiced by James Cromwell.

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, the Institute of Technology, with Tadashi and his younger brother 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 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 microbts, Callaghan accepts Hiro into the university. After the presentation, a 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 presumed dead.

Callaghan, as Yokai, 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 can 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 a window. Hiro explains the matter to a local police station, but is met with disbelief by the cop he tries to explain the matter to.

Hiro is still devastated about the loss of his brother, and theorizes that Yokai stole his microbots, then caused the fire in Tadashi's showcase to cover his tracks. 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 sees Yokai gathering massive parts from the nearby bay with the microbots. Suddenly, the rest of Tadashi's friends (GoGo Tomago, Honey Lemon, Wasabi, 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 drive off, in hot pursue by Yokai who 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 them dead, leaves.

Baymax saves Hiro and his friends by discarding his armor and using his buoyant balloon body to float up to the surface. Baymax reveals that he scanned Yokai before they sunk and has information on him, and they retreat to Fred's house, surprisingly a mansion. Planning to do a mass scan on San Fransokyo to find out his identity, Hiro builds a new suit for Baymax, equipped with offensive capabilities and rocket-propelled flight, and designs suits for his friends, organizing 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, 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 is launched inside as it does, leading to her death. This leaves Big Hero 6 to assume that Krei is the guy under the mask. Before the feed continues, Yokai suddenly appears, armed with the microbots, and yet again attempts to crush the heroes. Hiro and everyone else fight Yokai, ending with Hiro and Baymax flying into Yokai and knocking off his mask. As they get up, Yokai turns and reveals his true identity as Callaghan. Realizing that Callaghan was the one who caused the fire that killed Tadashi, Hiro confronts him for this, only for the professor to dismiss Tadashi's death as his own fault. Out of complete rage, Hiro tosses away Baymax's healthcare chip and orders him to kill Callaghan. Baymax goes out of control and attempts to kill Callaghan, but the other members try to stop him, forcing Callaghan to flee. Baymax is forcefully stopped and Callaghan reclaims his mask to use the microbots to escape, much to Hiro's dismay.

Hiro is angry at his friends for interfering and flies off with Baymax, leaving the others behind. After trying so many failed attempts to gain access to his access port, Baymax asks if killing Callaghan is what Tadashi would've wanted. After Baymax show a video compilation of Tadashi making improvements, making Hiro regain his senses and realize that killing Callaghan won't do any good. Big Hero 6 regroups and looks over the video feed again. It shows an apparently furious Callaghan storming into the building, roaring at Krei about how the machine "wasn't ready" and that he was using it without consent. The building was quarantined by the government, and the test pilot is revealed to be Abigail Callaghan, the professor's daughter. It was then Big Hero 6 realized that Abigail's apparent death drove Callaghan to a point of vengeful grief, 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. Callaghan, again as Yokai, suddenly intercepts, seizing Krei and dragging him into the air and directly confronting Krei about his daughter's death. Callaghan takes the remains of the teleportation machine and builds it over Krei Tech's building, intending to destroy it and draw in its remains to get back before killing Krei himself. Big Hero 6 arrives, and Hiro tries to talk Callaghan down, admitting that he understands his pain and knows the feeling of loss. Though Callaghan appears momentarily considering stopping, he opts instead to kill both Krei and the Big Hero 6, using the microbots to pin down each member of Big Hero 6. In a climactic final battle, Hiro has everyone works at different angles, succeeding into 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 the 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 his daughter one last time before being driven off in a police car, and his facial expressions hint he feels remorse for his crimes as he awaits to be given a long lifetime sentence in prison for his crimes.

Personality
Callaghan initially appears to be a friendly, genial teacher befitting his appearance. He clearly looks for potential in his students, and displays a measure of cunning manipulation in the means of subtly telling off Hiro for using his intellect in illegal bot-fighting. Callaghan was also an inventive, brilliant and presumably revolutionary man, responsible for coining Callaghan's Laws of Robotics. He was presumed famed for these reasons, as Hiro was immediately starstruck upon learning who Callaghan was.

Behind this, however, Callaghan was tortured, brooding and merciless. He was an immensely tragic figure motivated by the loss of his daughter to Krei's misuse of Project Silent Sparrow, leading to a bitter, murderous resentment of Krei and a lust for vengeance. As Yokai, Callaghan was resoundingly stoic and ruthless, a no-nonsense individual never saying so much as a word in his attempts to kill Big Hero 6. He employed ambush as much as he did brute force, and never let up in his assaults.

Callaghan had become a dark reflection of Hiro, an individual who was racked with grief after the loss of a loved one and thus sought revenge. However, while Hiro learned from his mistakes and accepted his loss, Callaghan's morals had been too thoroughly drowned, instead letting his lust for vengeance consume him. He callously dismissed Tadashi's death as his own mistake, and refused to accept that his daughter's loss needed to be accepted, ignoring Hiro's pleas to do so. However, upon seeing his daughter safe and realizing all his senseless destruction was for nothing, he seemed to show fault for his actions, implying immense remorse.

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

Appearance
Yokai appears as a shady, tall 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 swarm 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 Disney film Atlantis: The Lost Empire, hinting at his true nature.

Trivia

 * 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, means "spirit" or "demon" in Japanese.
 * Callaghan acts as an evil counterpart to Hiro. Both are genius inventors who end up suffering a major loss of a loved one (Tadashi for Hiro and Abigail for Callaghan). However, while Hiro learns to accept his loss and change before he can fall into evil, Callaghan stubbornly refuses to accept that Abigail is gone, having been pushed too far into corruption to change. However, upon seeing his daughter while being arrested, he seems to show guilt, hinting that he may change or not.
 * In production, Callaghan was originally known as Dr. Martin Lebur.
 * Among the script and concept arts of Yokai, some of them depicted Yokai with slighty different powers: Instead using mass of microbots, he uses what appeared to be liquid, living biomass that similar with Symbiotes from Marvel Comics, but how he control them is nowhere to be different.
 * Originally Callaghan/Yokai was going to put together a team of San Fransokyo's greatest criminals including Mr. Yama, but was changed to a solo act.
 * He is also similar to Loki from Thor, they were innocent from start, but then they turned evil and which makes them the true villains of those films.