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 also the former archenemy of Hiro Hamada and Baymax.
