Zuul

"I am the Gatekeeper."

- Zuul to Vinz Clotho. "There is no Dana, only Zuul."

- Zuul to Peter Venkman while in possession of Dana Barrett's body.

Zuul the Gatekeeper is one of the two main minions of the powerful demonic being known as Gozer and one of the secondary villains of the original Ghostbusters movie, and she and her male counterpart Vinz Clortho are part of the demonic race of hellhounds known as Terror Dogs. Zuul is known as the "Gatekeeper of Gozer" and is considered by many to be a female entity due to the fact it possessed a female victim and its role as the "Gatekeeper".

History
It was worshipped by the Sumerians and Hittites in 6000 BC, along with Gozer before he and his followers were overthrown by the Babylonian goddess Tiamat and her followers and thus banished to another dimension.

Centuries later, Zuul rewakens from its statue-like hibernation after a spirit was seen in a strange temple within another dimension by Dana Barrett from her refrigerator at her 55 Central Park West apartment calling out for her. Zuul later attacked and possessed her inside of her apartment and began seeking out Vinz Clortho, the Keymaster who had likewise possessed Louis Tully's body - the union of these two monsters would spark the necessary power to release Gozer into the mortal world and begin the apocalypse.

Zuul had originally sought out Dana as an apparition inside of her refrigerator when it laid in front of Gozer's Temple and growled the name "Zuul" at a terrified Dana, causing her to seek the Ghostbusters help. Afterwards during a fierce thunderstorm, Zuul manifested itself physically by "hatching" out of one of two dog-like gargoyles sitting atop the Shandor Building in front of the Temple of Gozer. Later that night, Dana had arrived at her apartment exhausted and laid back on her sofa when, suddenly, demon claws ripped through the sofa arms pinning her as  Zuul burst out of the kitchen door. A horrified Dana screamed as her sofa  slid into the kitchen where The Gatekeeper attacked and inhabited her.

While possessing Dana's body, Zuul was able to speak, but could not access Dana's memories or knowledge. She took on the identity of The Gatekeeper and proceeded to wait for Vinz Clortho, The Keymaster, another minion of Gozer who had possessed the body of Louis Tully, Dana's neighbor. While lying in wait of The Keymaster, Zuul was visited by Peter Venkman, who had arranged a date with Dana Barrett prior to her possession. Peter immediately noticed the radical change possession had caused in Dana, who was now wearing a very revealing red dress and was aggressively seducing him from the moment he opened the door. Peter lied to gain entry to the apartment, telling Zuul he was a friend of The Keymaster. Zuul introduced herself as "The Gatekeeper" and told Peter of their plans to prepare for the coming of Gozer, "The Destructor". Zuul laid down on her bed, seducing Peter aggresively however he did not reciprocate her lustful intentions and instead focused on attempting to talk to "Dana". At first Zuul dismissed his attempt before attempting to seduce him once more but Peter refused and restrained her to the bed instead. His persistence made Zuul increasingly angry and frustrated. Zuul (in Dana's body) announced in a demonic voice, emphatically growling at Peter that "There is no Dana, only Zuul!". Peter recoiled briefly before giving her to the count of three to release Dana. With each successive count, Zuul further manifested her demonic nature within Dana's body, first by turning her eyes white while snarling, then by thrashing her head while panting like a beast and finally by growling and snarling uncontrollably while levitating off her bed. Zuul unleashed her frustration with a barrage of inhuman growls before turning over in midair to stare down at Peter, who had the nerved to ask her to come down to which Zuul replied with a vicious roar.

Zuul was sedated by Peter and remained asleep until Walter Peck shut down the Ecto-containment unit, allowing The Keymaster to escape. Upon the release of all of the ghosts Zuul awoke and gazed at the events from her living room window; as beams of supernatural energy flew past her window Zuul unleashed another monstrous roar which caused her living room windows to explode outwards. As Zuul stared through the wreckage of the apartment, Vinz searched for her until finally locating her. He burst through the door to Dana's apartment to find Zuul laying seductively on the sofa. He presented himself to a grinning Zuul and the two demons shared a passionate kiss before walking up a hidden staircase leading to the rooftop where they finally consumated their satanic union. Post-coitus the demonic couple opened the gateway to the Temple of Gozer, transforming afterwards into their true demonic Terror Dog forms before taking their place next to Gozer, who entered through the gate with the intent of destroying the world.

After Gozer was defeated by the Ghostbusters, Zuul disappears from this dimension and Dana Barrett is transformed back into a human being, having no recollection of the events that took place since her and Louis' demonic possession.

Trivia

 * Zuul is referenced in What in Samhain Just Happened?! on page eight. Janine's Car's license plate reads "GBI ZUL".
 * On page 17 and 19 of Ghostbusters Issue #3, Zuul is referenced by Idulnas and in the Spates Catalog entry for Idulnas. It is said Idulnas' power eclipsed that of Zuul.
 * Zuul is a part of one of the Nostalgia Critic's running gags, whenever the movie he reviewed introduced a demonic creature (usually dog-formed), he would mimic Zuul by saying, "ZUUL, MOTHER**KER! ZUUL!!" There are also several variations of the gag.
 * Despite being a minion of Gozer, Zuul enjoys quite a large fanbase and the name is well-known even to those who are not active Ghostbusters fans due to it often being parodied or referenced in other works.