Eileen Leahy

Eileen Leahy (1985 - 2017) was an Irish-American hunter and the only daughter of Padraic and Maura Leahy, who lost her parents, as well as her hearing, to a Banshee as a child and became a hunter for revenge. She becomes an ally of the Winchesters and also was a legacy, as her grandfather was a Man of Letters.

Early Life
Eileen was born in 1985 at County Cork, Ireland. When she was still a baby, a Banshee broke into her home and attacked her father who had recently had a nervous breakdown due to losing his job. Eileen's mother was the daughter of a Man of Letters and knew some basic spells so she cast a banishing spell as the creature went after Eileen. The spell saved Eileen at the cost of her mother's life, but Eileen was rendered deaf from the Banshee's scream.

After her parents' deaths, Eileen was found by a hunter named Lillian O'Grady who had been hunting the Banshee. Lillian raised and trained Eileen to be a hunter before dying of cancer when Eileen was 16. Following her death, Eileen continued hunting the Banshee on her own for the next 14 years. Over the years, Eileen hunted several Banshees, but never found the one she was looking for.

Season 11
Eventually, Eileen tracked the Banshee to Oak Park Retirement Living in Lebanon, Kansas where the Banshee was feeding on the residents. Disguising herself as an employee named Marlene who was on vacation, Eileen investigated the two murders committed by the Banshee there and mistook Sam and Dean Winchester for two Banshees working together. Eileen trapped Sam who recognized her as a hunter and convinced her they were on the same side.

As Eileen bonded with Oak Park resident Mildred Baker, Sam realized that Mildred was likely the Banshee's next target due to a heart problem leaving her vulnerable and Mildred agreed to be their bait to lure the Banshee out. While preparing a spell to trap the Banshee, Sam and Eileen discussed revenge and Sam's own experience with it. Eileen showed uncertainty as to what she'd do once she got her revenge, telling Sam that while she didn't know her parents, they were still family.

That night, the Banshee attacked, but went after Dean rather than Mildred as was expected. As the Banshee was working on getting Dean to bash his head in, Eileen signaled Mildred to activate her spell. Mildred trapped the Banshee, allowing Eileen to kill it with a gold blade and get her revenge.

Following the death of the Banshee, Eileen told Sam that even though she got her revenge, her parents were still gone and killing the Banshee wouldn't bring them back. Rather than going on to a normal life, Eileen told Sam she was going to continue hunting as she was good at it and could help people. Sam invited her to drop by the Bunker sometime since she was a legacy and they joked about her deafness.

Season 12
Eileen is revealed to have kept in contact with the Winchester brothers and both have gotten better at sign language. Recently, Eileen dealt with a demon that had burnt down a warehouse and killed a doctor. The trio realize that this demon is linked to Dagon, a Prince of Hell who is protecting Kelly Kline. Sam decides to lure Kelly into a trap and they manage to capture her. Eileen also meets British Men of Letters Mick Davies and Renny Rawlings who have come to help in dealing with Kelly's unborn son. However, their meeting is interrupted by Dagon who has come back for Kelly. Dagon sends everyone flying into the distance and grabs hold of Kelly. Eileen recovers in time to grab The Colt. She tries to shoot Dagon but the Prince disappears, causing the Eileen's bullet to hit Renny instead.

As per protocol, Mick attempts to kill Eileen in retaliation but Sam convinces him not to. With Kelly gone, Sam and Dean return to the bunker with Eileen, who is distraught over her actions. Sam comforts her. She decides to return to Ireland for a while following the incident but leaves the Winchesters the Colt which she had kept after killing Renny.

In There's Something About Mary, Eileen comes under attack by a hellhound commanded by Arthur Ketch in South Carolina. Despite her best efforts, Eileen is killed by the hellhound. The Winchesters are later informed of her death by Sheriff Jody Mills. She's the second hunter death heard of by the Winchesters in three weeks, drawing their suspicions especially since they recognize her wounds as having been caused by a hellhound.

The Winchesters later receive a letter sent by Eileen through normal mail as she had realized that her phone and computer were being monitored by the British Men of Letters. Eileen's letter, sent four days before, reveals that she had returned to the United States in fear of her life and hoping to seek refuge with the Winchesters. Their own suspicions drawn by Eileen's letter, the Winchesters search the Bunker and find Arthur's monitoring equipment. After capturing Lady Toni Bevell, the Winchesters question her on Eileen's murder. While Toni admits she doesn't know who Eileen is, she tells them that if they suspect her organization of having killed someone, they are likely right.

Personality
Despite being rendered both deaf and orphaned by a Banshee, Eileen is a strong-willed young woman capable of holding her own. She was able to take Sam down by surprise and confront her parents' murderer with nothing but determination. She can be ruthless to enemies and friendly to allies, making her a dangerous foe and a highly reliable companion.

Eileen's tough exterior does not completely hide a more fragile, caring side. Eileen was completely distraught upon accidentally killing Renny, and could not easily get over it. Besides being a tough and good-natured hunter, Eileen is also sassy and very self-confident.

Physical Appearance
Eileen is a short, dark-haired caucasian woman. In her first appearance, she wore a maid disguise and later a typical hunter's outfit consisting of a shirt, trousers and a jacket. Like the Winchesters, Eileen also wears plaid shirts.

Powers and Abilities

 * Spell Casting - Eileen was able to cast at least a powerful binding spell, having been taught by Lillian O'Grady.
 * Expert Hunting Skills - Having been raised by a hunter, Eileen was a skilled hunter herself.

Appearances

 * Season 11
 * Into the Mystic
 * Season 12
 * The British Invasion
 * Twigs & Twine & Tasha Banes
 * There's Something About Mary
 * Season 15
 * Golden Time
 * Our Father, Who Aren't in Heaven

Trivia

 * She is the first deaf hunter to be introduced on the series.
 * She is the fifth female ally of the Winchesters. The first one was Jo Harvelle and her mother Ellen Harvelle followed by Jody Mills and Charlie Bradbury.
 * Both Charlie and Eileen were created by Robbie Thompson.
 * Coincidentally, both Charlie and Eileen became hunters, Winchester allies, and fan favorites.
 * They both die in episodes written by Eugenie Ross-Leming and Brad Buckner.
 * Charlie and Eileen were born in the same year.
 * Stern believes Eileen felt the hunter lifestyle to be solitary, until she met Sam and Dean.
 * Stern said Eileen owned a "girly version" of the Impala, a car of her own that wasn't shown until episode The British Invasion, where it was revealed to be a red 1971 Plymouth Valiant, ala the iconic 'Duel' car. The car returns in season 15, where actress Stern specifically requested the same car be brought back for her.
 * Her name was pronounced differently by the Winchesters in Season 11 and Season 12.