Zuul

Zuul - also known as The Gatekeeper - is a demonic entity from the film Ghostbusters. This creature is a minion of Gozer, an ancient Sumerian deity destined to destroy the world. Whenever Gozer traveled to a new world, it sent its acolytes Vinz Clortho and Zuul ahead to prepare that world for the Destructor's coming. When it manifested in the material world, Zuul took on the form of a Terror Dog.

History
In 1984, paranormal activity rose dramatically in New York as Gozer the Gozerian approached Earth from across the astral plane. At this time, three scientists - Peter Venkman, Ray Stantz and Egon Spengler - had opened up their own paranormal investigation and elimination business: Ghostbusters Inc.. Their first client was Dana Barrett, a woman who lived at an apartment complex at Central Park West who informed the Ghostbusters that she had seen a demon in her refrigerator, which had called out the name 'Zuul '. While Dr. Venkman investigated Dana's apartment and found no abnormal spiritual energy readings, he and his colleagues would continue to look into the case, eventually learning about Gozer. Weeks later, a thunderstorm occurred and Zuul manifested on the roof of the Shandor Building. While Dana was getting ready for a date with Dr. Venkman, Zuul entered the apartment and possessed her. Venkman arrived later on and Zuul, in Dana's body, greeted him, asking if he was the "Keymaster". Peter initially said no and Dana closed the door on him, but he would knock again and Dana would repeat her question. This time, Peter said yes and was brought inside. Realizing that something was wrong, Peter questioned Dana, who referred to herself as Zuul and told him that Gozer was coming. Peter tried to convince the demon to let him speak to Dana, but Zuul denied him. When Peter kept talking, Zuul levitated off of Dana's bed, ferociously barking at Venkman, who then managed to inject Dana with a large dose of thorazine to knock her out.

The next morning, Walter Peck of the Environmental Protection Agency came to the Ghostbusters' firehouse in order to shut down the Ecto-Containment Unit. Despite the protests of Drs Venkman, Spengler and receptionist Janine Melnitz, Peck shut off the containment grid, causing an explosion of spiritual energy and the release of all the captured ghosts. In the chaos, Vinz Clortho - who had possessed Dana's neighbour Louis Tully - escaped and wandered back to the Shandor Building. When he arrived, he was greeted by Zuul. The two embraced and kissed passionately before ascending a secret stairway leading to a gateway on the roof from which Gozer was to emerge. That night, the Ghostbusters arrived at the Shandor Building's rooftop where they witnessed Louis and Dana transform into Terror Dogs and take their places flanking the gateway as Gozer emerged. They remained in place like stone gargoyles while the Ghostbusters fought against Gozer. After the team crossed their particle streams and destroyed the gate, Gozer and its minions were banished and Louis and Dana were restored to normal, singed from the explosion and buried under the debris of the hollow gargoyles, but otherwise unhurt.

Personality
Zuul seemed to be the more intelligent of Gozer's minions. For the most part, she was even-tempered when she met Peter Venkman, though became clearly frustrated when Venkman kept talking and asking to speak with the demon's host vessel, claiming "There is no Dana, only Zuul". Zuul even behaved in quite a seductive manner, apparently open to the possibility of sex with Dr. Venkman after allowing him into Dana's apartment.