The Birth: Very often an incident in childhood suggests the sort of person the child will be when he grows up. Such was the case with Jonathan Crane. As a small boy, he liked to frighten birds. As Crane grew, his passions for causing fear and reading books intertwined. He studied evil, terror and man's inhumanity to man. After studying hard, Jonathan Crane went on to become a professor of psychology at Gotham University. But his whims of causing fear never ceased. He became a first rate teacher, though other professors balked at his methods.
He spent every cent he earned on books and had little time for his own personal attire and well being. It was when he overheard other professors talking about his queer nature that he became totally unhinged. He had heard that they once said he looked like a scarecrow - and that stuck in his mind. He adopted the name as his own. He became the Scarecrow - a symbol of poverty and fear combined.

The Legend: Soon after taking the identity of the Scarecrow, Jonathan Crane hired himself to a businessman named Kendrick. Kendrick was facing a lawsuit filed by his ex-partner which would prove to be quite disasterous. So he asked Scarecrow to either make his former parter; Paul Herold, drop the suit or finish him. The Scarecrow put fear into Paul Herold to make him drop the case. But since he didn't back down, the Scarecrow shot the man. And that was the begining of his life as a criminal.
The Scarecrow has no super powers. The only weapon he uses now is a fear gas that he invented. The gas induces fear into people, making them see their worst nightmare.
Scarecrow has been in and out of Arkham Ayslum, but he keeps on reverting to his old habits. He mainly gets on the wrong side of the Batman. Of course, he once used his fear gas on the Batman, but that only made Bats more angry and more deadly. The Scarecrow was at the time partnering with the Joker and Bats; induced by the gas, relived the time when the Joker mowed down Jason Todd; the second Robin and he hit back with all the vengence he could find.