Scarecrow is one of Batman’s greatest enemies. As a child, he was bullied and tormented, so he decided to research the human psyche and how people dealt with fear. After being fired from a teaching position, Crane decided to use his knowledge to literally scare people to death for the supposed trauma he suffered in his life. Typically using some form of his potent fear gas, Scarecrow has previously manipulated fellow villains such as Joker, Poison Ivy and Killer Croc to fight his enemies. Even Batman has proven susceptible to Scarecrow's chemicals.