Jennet Humfrye

The Woman in Black is the titular spirit, and the main antagonist of the film of the same name, as well as its 2015 sequel.

Description
The Woman in Black appears when children die. She manipulates the children into killing themselves, and it is stated that she has control over their souls after their deaths. It was revealed that in life, The Woman in Black was a woman named Jennet. She was found to be mentally troubled and wasn't considered suitable for taking care of her son Nathaniel. Alice, her sister, takes Nathaniel and treats him as though he were her own son. One day, Nathaniel drowned in the Marsh, and Jennet hung herself. When the protagonist, Arthur Kipps, found out that his son Joseph was her next victim, he dove into the Marsh in order to retrieve Nathaniel's body in hopes that she will have closure. He does finally retrieve the body, and returns it to Jennet. However, she said that she would never forgive.

While waiting for the train, Joseph walks into the train tracks while the train was arriving. Arthur tried to get his son back. The result is both of them dying, and reuniting with his deceased wife. And The Woman in Black looks on in implied anger. It's possible that since Arthur tried his best to appease Jennet, she allowed him and his son to pass into heaven rather than take their souls.

Trivia

 * She is similar to the Creepypasta monster, Mr. Widemouth, who also brainwashes children into committing suicide.