Big Hero 6 - Ending Explained

The central mystery reveals that the masked villain, Yokai, is actually Professor Robert Callaghan, who was presumed dead in the fire that killed Tadashi. Callaghan survived by using Hiro's microbots to shield himself, leaving Tadashi to die in the explosion. His motivation is not world domination, but revenge against tech mogul Alistair Krei, whom he blames for the loss of his daughter, Abigail, in a failed teleportation experiment. In the climax, Hiro and Baymax enter the unstable portal to save Abigail, who is found alive in hyper-sleep. To save Hiro and Abigail, Baymax sacrifices his physical body, using his rocket fist to push them back through the portal. The twist of hope comes when Hiro discovers Baymax's healthcare chip clenched in the rocket fist, allowing him to rebuild Baymax's body and restore his original personality, effectively bringing his friend back.

Some critics view the film as a critique of the traditional superhero origin. Instead of the hero's trauma leading directly to righteous crime-fighting, the film shows the 'vigilante phase' as a dangerous, emotionally unstable reaction to grief that must be corrected. Additionally, the villain Callaghan acts as a Dark Reflection of Hiro—showing what Hiro would have become if he hadn't listened to his friends: a man willing to destroy everything for the sake of a lost loved one.