Zuul

Zuul is one of the two main henchmen of the arch-demon known as Gozer and one of the main villains of the original Ghostbusters movie, part of the demonic race of hellhounds known as Terror Dogs. Zuul is known as the Gatekeeper 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".

Zuul possessed Dana and sought out Vinz Clortho, the Keymaster in 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.

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.