The Scarecrow/Dr. Jonathan Crane

In the 2005 film Batman Begins, as well as the 2008 film The Dark Knight, he was played by Cillian Murphy.

Scarecrow (Dr. Jonathan Crane) is an inane former psychiatrist who uses a variety of drugs and psychological tactics to exploit the fears and phobias of his adversaries. He does not commit his crimes for wealth, but rather as a form of "research" to further study the effects of fear on humans, making the innocent citizens of Gotham City his unwilling guinea pigs.

While he will occasionally commit robbery or other types of larceny, he does so only to get the funding he needs to carry out his experiments. Like many of the Batman villains, he has become a much darker character over the years.

Crane is a psychiatrist with a specialty in phobias. Using a variety of toxins that cause his victims to hallucinate that their phobias have come to life, the Scarecrow can instill fear in all who see him. However, recently he has displayed the ability to literally frighten people to death without relying in the chemical, suggesting a great ability to dominate the human psyche using fear as a weapon.

In Batman Begins, the fear toxin he uses is extracted from a mountaintop blue flower from Tibet, and only works in vapour form. Crane uses his Scarecrow mask to enhance the effect of the hallucinogen as well as to avoid being poisoned by his own toxin.

As the Scarecrow, Crane wears a mask, seemingly a poorly-stitched burlap sack with a hangman's noose dangling around the neck. The mask has a built-in rebreather and acts as a gas mask, and enhances the effect of the hallucinations in his experiments