Robert Callaghan

Full Name

Robert Callaghan


Yokai, Professor Callaghan


Avenge his daughter's disappearance by killing Alistair Krei


Apprehended and arrested for his crimes

I want my daughter back!
~ Robert Callaghan

Professor Robert Callaghan, also known as Yokai is the main antagonist in Big Hero 6. He is the former head of San Fransokyo's Institute of Technology, and the super-villain Yokai.



Professor Robert Callaghan was a renowned scientist known for his creation of Callaghan's Laws of Robotics. Callaghan used his knowledge of robotics to become the head professor of the San Fransokyo Institution of Technology. At one point, Callaghan's daughter, Abigail, was used as a test pilot for Krei Tech Industries, run by Alistair Krei. One of Krei's ambitions at the time was the creation of teleportation through the use of portals. However, during an experimental test run, a malfuction occurred in the system, and Abigail vanished in the portal and was presumed deceased. 

After his daughter's supposed death, a grief-stricken Callaghan swore revenge on Krei, blaming him for Abigail's disappearance. 

Big Hero 6

Callaghan is first introduced at the San Fransokyo Institude of Technology, where he is introduced to Tadashi's younger brother, Hiro Hamada, a young genius. Realizing Hiro's potential, Callaghan convinces him to join the school alongside his brother. To gain admission into the school, Hiro shows off his new invention, the Microbots, an army of miniature bots capable of becoming anything the mind can conceive, at the school student showcase. This invention impresses Callaghan, though they also attract the attention of Alistair Krei, who offers to buy Hiro's inventions. However, Callaghan convinces Hiro to reject the offer, and accepts him into the university.

After Hiro's departure, Callaghan steals the Microbots for his own nefarious purposes, and sparks a fire in the showcase hall, setting the building aflame. Tadashi is killed in the fire when he attempts to rescue Callaghan, and the professor is presumed dead as well. However, Callaghan survives the fire, and sets up a base of operations in an abandoned warehouse to enact a plot of vengeance against Krei, under the guise of Yokai. He begins mass-producing an army of Microbots to aid in his goals. One day, Hiro and his healthcare robot, Baymax, discover the army of Microbots in the warehouse, and barely manage to escape upon being noticed.

Determined to stop Yokai, Hiro transforms Baymax into a crime-fighting robot and the duo head out to the warehouse to apprehend Yokai. However, Tadashi's friends arrive on the scene, alerting Yokai to their presence. A chase ensues, during which the group manage to escape by driving their car into the sea. Yokai, believing them to be dead, departs from the scene. However, the group survives and use their knowledge of technology to become a superhero team known as Big Hero 6.

Yokai infiltrates the abandoned facility of Akuma Island, which once belonged to Krei. Big Hero 6 arrive at the facility, and find a recording of Abigail's supposed death during the test run, which they learn resulted in the closure of Krei's facility. This leads the group to believe Krei is Yokai. Just then, Yokai appears and a battle ensues, which culminates in Hiro managing to remove Yokai's mask, exposing him as Callaghan. Hiro, horrified at the realization that Tadashi died for nothing, along with Callaghan's lack of empathy, removes Baymax's healthcare chip and turns him into a mindless killing machine, ordering him to kill Callaghan. As the group attempts to stop Baymax, Callaghan retrieves his mask and flees the scene. 

The following day, Yokai intercepts Krei's latest ceremony and captures the tech-guru, revealing himself as Callaghan. Callaghan announces his plot to use the rebuilt portal to destroy everything Krei has ever built, before killing Krei himself. Despite Krei's pleas for mercy, Callaghan activates the portal, which begins to destroy the building and everything around it. Just then, Big Hero 6 arrives and confronts the former professor, pleading for him to call off his revenge plot as Abigail wouldn't approve. However, Callaghan refuses and a battle ignites between him and Big Hero 6.

Though initially overwhelmed, Big Hero 6 manage to suck the Microbots into the portal, rendering Callaghan without a power source. Rendered powerless, Callaghan prepares to be killed by Hiro and Baymax, but they relent, deciding to spare his life. However, Baymax destroys Callaghan's mask, eliminating his remaining Microbots and descending the portal. However, the portal becomes unstable, prompting everyone to flee. Baymax, sensing life within the portal, enters the poral with Hiro, and discover Abigail, still alive. They rescue her and manage to bring her to safety, though Baymax is forced to sacrifice himself to allow the other two to escape. 

Callaghan is arrested for his crimes and shove him into the back of a police car. Before being taken into custody, Callaghan manages to see his daughter one last time, and hangs his head out of grief and remorse for his actions.


Evil but caring, only towards his daughter he will show love.

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