According to Irish folklore, the Glostic Sisters were a pair of wandering spirits. One was a Banshee, the other a Siren. Banshee requires the youth of mortals to sustain her strength. Siren is the only one who can provide it.  Together they eluded detection throughout the centuries until the 20th century.   In 1997, Banshee was heard at the Metropolitan Opera House and fought the Extreme Ghostbusters. She managed to escape but was aged by direct hits from the Proton Streams. In Central Park, she met up with Siren and was partially rejuvenated. Hungry for more, Banshee forced Siren to seek out a larger source of youth to take from.
Meanwhile, at the Firehouse, a Subharmonic Acoustic Scanner was rigged to trace Banshee's isolated vocal frequency. The Ghostbusters traced Banshee to a Syren concert, not realizing the connection yet. Due to a limit in funds, only Roland Jackson entered the concert. Banshee caught sight of him and tried to flee the scene only to be sighted by Garrett Miller. After a deadly rooftop battle, Garrett managed to trap the Banshee and she was placed into the Containment Unit.
While the Ghostbusters gathered to equip themselves with special earmuffs, Roland freed the Donkey ghost, Gas ghost, and the Banshee. He was still under Siren's hypnosis and believed she and Banshee belonged together. After Banshee was rejuvenated again, she demanded more youth and took Siren to the Harvey Finkel High School, where a basketball game between the Rams and Trojans were taking place. Invigorated by the youth, Banshee overpowered the Ghostbusters but Kylie Griffin was able to reason with Siren. Siren took back the youth and rapidly aged Banshee into a hag. She then willingly went into a trap and released her hold on all victims. Banshee then tried to attack Roland but the other Ghostbusters re-trapped her. Banshee was returned to the Containment Unit where it appears she submitted to the authority of Surt.
Banshee was a mean older looking woman, that was nasty and careless about anyone other than her sister, some of the time. She was raven-haired and dressed in black shrouds.
- She isn't the only Banshee as the original Ghostbusters had a Banshee to deal with which makes it a type of creature that is either solitary or part of a pair.
- ↑ Kylie Griffin (1997). Extreme Ghostbusters- Sonic Youth (1997) (DVD ts. 03:56-03:59). Sony Pictures Home Entertainment. Kylie says: "For your information, that screaming chick was a Banshee."
- ↑ Egon Spengler (1997). Extreme Ghostbusters- Sonic Youth (1997) (DVD ts. 09:35-09:44, 10:07-10:13). Sony Pictures Home Entertainment. Egon says: "I'm guessing you didn't make it to my chapter on the Glostic Sisters. According to Irish folklore, they were a pair of wondering spirits. One was a Banshee. The other, a Siren...Banshee requires the youth of mortals to sustain her strength. Her sister is the only one who can provide it."
- ↑ Syren (1997). Extreme Ghostbusters- Sonic Youth (1997) (DVD ts. 02:54-02:57). Sony Pictures Home Entertainment. Syren says: "We've eluded detection all these years."
- ↑ Banshee (1997). Extreme Ghostbusters- Sonic Youth (1997) (DVD ts. 03:33-03:36). Sony Pictures Home Entertainment. Banshee says: "I've taken us this far through the centuries."
- ↑ Egon Spengler (1997). Extreme Ghostbusters- Sonic Youth (1997) (DVD ts. 04:00-04:04, 10:07-10:13). Sony Pictures Home Entertainment. Egon says: "An Audio-Sonic Non-Vaporous Free Floating Apparition to be precise."