Jason Voorhees, the son of Pamela Voorhees, was born deformed. He lived with his mother at Camp Crystal Lake (his mother was the camp cook), in the city of Crystal Lake. Jason was bullied incessantly until, in 1957, he tried to prove to the bullies that he could swim and drowned in Crystal Lake.
One year later two of the Camp Crystal Lake counselors were murdered and the camp was shut down. Future attempts to reopen the camp were plagued with problems, including poisoned water and unexplained fires.
In 1980 eight new counselors planned to reopen the camp, but ultimately all but one of the new counselors were murdered. The killer is ultimately revealed to be Pamela Voorhees. Pamela is then beheaded by the only survivor, Alice.
The very next year Alice is murdered by an unseen killer in her home. Five years after Alice's murder a group of counselors return to Camp Crystal Lake for training, and all but 2 are murdered (though one of the survivors cannot be found). The killer turns out to be Jason Voorhees. Full grown and seemingly indestructible, Jason kills to avenge his mother's death and to carry on her quest to keep the camp closed.
In each new incarnation Jason returns to be an unstoppable killer, only to be "killed" then later resurrected.
http://www.imdb.com/character/ch0002146/bioThe Scarecrow (Dr. Jonathan Crane) is a mentally unstable former psychologist who uses a variety of drugs and psychological tactics to use 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 his unwilling guinea pigs.
Scarecrow's chief weapon is a toxin he created called fear gas. With it, he can cause his victims' worst fear come to life or, he can cause a person to fear something they didn't before, as when he caused two guards at Arkham to fear glass in order to break out. This substance is verstile as it has been used in gas, darts, capsules, etc. His mask was made in order to enhance the effects of the hallucinogen while also acting as a gas mask of sorts to keep him from poisoning himself. Even so, he seems to have formed an immunity to fear, which depresses him.
Though he doesn't do so often, Scarecrow is skilled in hand-to-hand combat. He uses a martial art he calls "violent dancing" which seems to be a mix of crane style kung-fu and drunken boxing, which makes use of his long arms and legs. He also uses farm implements such as pitchforks, sickles, or more commenly, scythes.
Scarecrow greatly understands the power and uses of fear. He even has a PhD in psychology. With this knowledge, he knows how to use words to affect a person's actions, once managing to drive two men to suicide with nothing but words. He also can use this insight to find people's mental weaknesses and exploit them. After some genetic manipulation done to him secretly by Dr. Linda Friitawa (also known as the criminal "Fright"), scarecrow gains the ability to turn into a large monster with greatly enhanced strentgh, endurance, and a fear gas he naturally emits. However, he has to be under physical strain or duress to transform.
http://batman.wikia.com/wiki/The_Scarecrow