Click To Help Maleficent
"Listen well, all of you!", "Yokai,"
is nothing more than an insignificant stub.
It is in desperate need of more content.
So says Maleficent:
the Mistress of All Evil.
Yokai transparent-0

Professor Robert Callaghan, also known as Yokai, is the hidden main antagonist of Big Hero 6. He is Hiro's arch-nemesis, Professor Krei's arch-rival, and Abigail's father.