In 1986 in County Cork, Ireland, she targeted the Leahy family as patriarch Padraic Leahy had recently had a nervous breakdown due to losing his job and was thus vulnerable. As the Banshee targeted Padraic, his wife Maura recognized that a Banshee was targeting her husband due to being the daughter of one of the Men of Letters.
As the Banshee forced Padraic to bash his own head in and began feeding on his brain, Maura began preparing a banishing spell. The Banshee telekinetically flung Maura into a bookshelf and turned her attention upon Padriac and Maura's baby daughter Eileen, seeing the baby as vulnerable as well. Before the Banshee could reach Eileen, Maura completed her banishing spell and banished the creature out of her house.
After the Banshee was gone, Maura died from slitting her own wrist to use her blood to complete the spell. Eileen survived, but the Banshee's scream rendered the baby deaf. Eileen was found by hunter Lillian O'Grady who had been hunting the Banshee but never found it. Lillian raised and trained Eileen who sought revenge upon the Banshee for killing her parents.
In 2016, the Banshee resurfaced in the Oak Park Retirement Living home in the United States where she began targeting residents. The Banshee killed Harold Miller, a resident who had recently had a hip replacement surgery. The attack drew Eileen's attention as well as that of fellow hunters Sam and Dean Winchester. The Winchesters originally suspected a vengeful spirit, but were proven wrong when the Banshee killed the heartbroken manager Arthur in front of resident Mildred Baker. The Winchesters quickly determined that they were dealing with a Banshee and learned of Eileen's connection to it.
That night, the hunters set up a trap in Mildred's room, believing she would be the creature's next target. Instead, moments after sunset, the Banshee focused her attack on Dean, presumably due to his attraction to the Darkness and his guilt over it. As the Banshee began forcing Dean to bash his head in, Sam and Eileen attempted to attack only to be thrown aside, albeit after Sam injured the Banshee's arm.
As the Banshee focused on Dean, Eileen signaled Mildred in sign language to active a trapping sigil painted on the wall. Upon activation, the sigil yanked the Banshee across the room and pinned it against a second sigil there. As the Banshee desperately attempted to break free, Eileen stabbed it in the chest with a gold blade. The Banshee exploded into dust and its power over Dean was broken in time to save his life.
In the aftermath, Eileen admitted that killing the Banshee felt like just another kill to her. While she got her revenge, the Banshee's death couldn't bring her parents back and Eileen decided to continue hunting and helping people.
Two years later, British Men of Letters operative Renny Rawlings recognized Eileen as "the Banshee girl" when they were introduced and explained that the British Men of Letters had a file on the incident.
Powers and Abilities
- Sonic Scream - She was able to produce a high-pitching scream that can hurt people who hear it. Humans affected by it are forced to bash their head in, effectively forcing them to commit suicide. Short-term exposure at close range rendered a baby deaf.
- Intangibility - Like spirits, she was intangible and is said to travel through mist.
- Camouflage - She was able camouflage to her surroundings. They are able to travel through the mist.
- Tongue - She had a long, and specially designed tongue to consume the brain of her victims.
- Invulnerability - She couldn't be killed by conventional means, she can only be killed with a gold blade.
- Electrokinesis - Her presence caused the lights to flicker and the power to go out anytime that she appeared. When the Banshee was killed, the power returned moments later.
- Telekinesis - With a single gesture, she was able to fling Eileen Leahy across a room into a bookshelf and Sam Winchester through a wooden door. She also flung Maura Leahy into a cabinet in the same manner.
- Flight - She moved about by floating through the air.
- Gold - A weapon of pure gold can kill a banshee. Just being slashed with a golden weapon hurts it.
- Banishing Spell - Can be banished by a basic spell.
- Celtic Blood Trapping Spell - Can trap a Banshee and appears to bind its powers.