Prime Evil was one of the original Dark Spawn Lords during the first Cartoonian War before Malefor and Cobra were created. He is also the self appointed leader of ghosts in Filmation's Ghostbusters. Prime Evil resides at Hauntquarters somewhere in the Fifth Dimension/Ghost Limbo.
He is by all accounts a nasty evil ghost with a dominating personality. He will on many occasions while talking make an electrical static sound (sort of a "Scrrrrrsssshhhkkk"). He is also known for being annoyed by ghosts that fail his missions. He will either punish the ghost in a thought out method relevent to the character (Such as pouring water on Sir Trance-a-lot which makes him rust), or he'll simply zap them.
Best described as a robotic grim reaper by way of He-Man's Skeletor, and with an oscilloscope in place of a mouth/jawbone. This futuristic / cybernetic element is a recurring theme amoungst some of Prime Evils henchmen such as Scared Stiff and Fangster.
He drove Jake Kong family to close a mine they had(from episode "The Headless Horseman Caper"). Prime Evil's first encounter with the Ghostbusters happened as the Senior Ghostbusters were training the next Ghostbusters in the mine. Prime Evil ended up trapped in the mines locked vault 100 years along with Brat-a-rat. However, he got out when he lied to Belfry and told him he was a bat.
Prime Evil is described in Our Buddy Fuddy as one of the greatest wizards who ever lived, second only to Merlin. His powers are indeed great; in most episodes he's completely immune to the Ghost Dematerializer. He's even shown to have the power to rematerialize his henchmen who've been affected by the weapon, although he most often does not do so out of his habit of punishing them for failure.
Role in the series
Prime Evil has not appeared in the series, but was first mentioned in the Origin of the Dark Spawn page on this wiki. Scroopfan may consider him to appear once he finds out who he is.