Long ago, a young and foolish woman named Una O'Neill offended Aibell by breaking the heart of a boy under her protection. Aibell told Una she would never in a dozen lifetimes find another as sweet and pure as him. Aibell condemned her to life. As part of the curse, Aibell sent one of her Banshees to keep Una alive every year by filling her with more time and more pain.   As a result, she lived for over 500 years. Una became a friend of Walter Peck's family at some point. Eventually, she wanted to pass on and asked Peck for help in doing so. Peter Venkman, Ray Stantz, Winston Zeddemore, and Kylie Griffin were brought in.
Peter and Kylie went to look for Aibell while the others fended off the Banshee sent to Una. Relying on the comprehensive lore and a pair of Ecto Goggles, Kylie found the entrance to Aibell's residence, Craig Liath. As Peter quoted a lyric from "Purple Rain" about how the times are changing, Aibell agreed. He turned and shot. The Proton Stream had no affect. Aibell was impressed with Peter's boldness and appeared to them. She inquired about the purpose of their visit. Lacking the proper equipment to fight a god, they did the next best thing: talk. At first she didn't recognize who Una was until they explained she was the one her Banshees were keeping alive. Aibell mused she would keep Una alive for three or four more lifetimes. She deduced they were a distraction while their allies tried to save Una in vain. Peter was not impressed by her kinda-sorta read your mind act. Aibell laughed and took a liking to Peter. Aibell agreed to abandon her claim on Una in exchange for a favor. Peter agreed before Kylie could stop him. Aibell teleported them to Una's property then ripped the Trap holding the one Banshee in half, releasing it. Aibell appeared on the face of the Moon and bid Peter goodbye then reminded him they would see each other again. Winston realized Peter did something that was going to catch up to them later. As the sun rose, Una passed on at long last.
Aibell sensed the power of the Rauoskinna after the Ghostbusters and Loftur Þorsteinsson were accidentally cast into Hell by Jenny Moran. After following the River Styx to its endpoint in an ice cavern, the Ghostbusters climbed down but they were all suddenly teleported to Craig Liath. Aibell appeared on her throne and called in the favor Peter owed her. She wanted the Rauoskinna. Janine Melnitz was resistant to giving it up until they were sure there was nothing that could help bring Egon Spengler back. The parallel Egon that was with them implied they had enough firepower to take on Aibell. Aibell was not interested in a fight. As a token of good faith, Aibell restored Egon to life. Peter handed over the Rauoskinna. Aibell believed it didn't belong in the mortal world and reckoned she would find a good use for it. Jenny thought the book was too evil and didn't trust it in Aibell's possession. She destroyed it with her Proton Stream. Aibell was infuriated and Jenny was torn apart by her angry wail.  She grabbed Peter and accused him of cheating her out of the favor. Peter caught her on a technicality and insisted he complied and gave her the book. She was at a loss for words. She tossed Peter on the Egons and sent them back to Umpire Rock in Central Park. She advised them to pray she never lay eyes on them again.
Aibell is a god and thus immortal. She has shown the abilities to take on a shadow form, project her visage, is unaffected by Proton Streams, commands Banshees, can mass teleport herself and others over vast distances in the physical realm or one realm to another, sense black magic, and atomization.
- Aibell is a Fairy queen/goddess from Irish mythology. She was the guardian goddess of Dalassians, Fairy Queen of Thomond, and presided over North Munster. She is said to dwell in a silent glen at Craig Liath, the "Grey Rock," two miles north of Killaloe.
- In Ghostbusters International #7, page 6 panel 2, Kylie mentioned Aibell commanded a whole horde. According to legend, Aibell commanded Clare's two dozen Banshees. 
- In Ghostbusters International #7, page 16 panel 5, a harp is on the right - a nod to Aibell. It is said if you hear her harp playing, you won't be alive for much longer.
- Aibell was mentioned in Jenny Moran's bio on the 20th Crossing Over Virtual Trading Card, released on April 26, 2018. 
- Aibell was alluded to in Death's bio in the 36th Crossing Over Virtual Trading Card, released on June 21, 2018. 
- Ongoing Series
- Ghostbusters 101
- Issue #2
- Alluded to by Ray on page 23.
- Issue #2
- Ghostbusters Crossing Over
- Una O'Neill (2016). IDW Comics- "Ghostbusters International #7" (2016) (Comic p.6). Una O'Neill says: "I offended the great and terrible Aibell - and she condemned me to life."
- Una O'Neill (2016). IDW Comics- "Ghostbusters International #7" (2016) (Comic p.5). Una O'Neill says: "The Banshee's been sent to keep me in the land of the living."
- Una O'Neill (2016). IDW Comics- "Ghostbusters International #7" (2016) (Comic p.5). Una O'Neill says: "Each and every year, one of Aibell's banshees comes to fill me with more time and more pain on her behalf."
- Ghostbusters 101 Class Notes (2017). IDW Comics- "Ghostbusters 101 #2" (2017) (Comic p.23). Ghostbusters 101 Class Notes reads: "Finally, there is Ms. Moran -- she's something wholly different, and this may well have something to do with the manner of her passing (which was being torn apart by the wail of an angry banshee before her time)."
- Ray Stantz (2016). IDW Comics- "Ghostbusters International #11" (2016) (Comic p.18). Ray Stantz says: "An encounter with two Class Sevens, a cursed artifact, an immortal wizard, and a trip to Hell besides, and we made through completely unscathed."
- Monaghan, Patricia (2014). Encyclopedia of Goddesses & Heroines, p. 178. New World Library, Novato CA USA, ISBN 1608682171. Line reads: "Afterward Aeval served as a Banshee, chief of Clare's two dozen banshees."
- TomWaltz Tweet 4/26/18
- TomWaltz Tweet 6/21/18
- Narrator (2016). IDW Comics- "Ghostbusters International #8" (2016) (Comic What Came Before! page). Narrator says: "There were banshees, sure, and Peter made a deal with a faerie."
- Walter Peck (2018). IDW Comics- "Ghostbusters Crossing Over Issue #1" (2018) (Comic p.12). Walter Peck says: "And I also know getting killed by a Banshee is a little bit more than just unfortunate - don't you think?"