Scarecrow is a brilliant psychologist turned super-villain who fights Batman in Gotham City, specializing in techniques and chemicals that manipulate fear. Jonathan Crane was originally a well-respected professor, although he lost credibility when he obsessively took his experiments too far and descended into madness, becoming obsessed with spreading and experiencing fear as the Scarecrow. His trademark fear gas is derived from plants, a fact that Poison Ivy and Swamp Thing both dislike him for.