Samhain

Samhain is the Ghost of Halloween and one of the few villains to face the Ghostbusters on more than one occasion. He is a strategic ghost with the ability to manipulate time in order to cause eternal night. Samhain also has the ability to control legions of ghosts at his command, however certain ghosts such as Slimer seem able to resist him to a certain extent.

Since his debut, Samhain has made many appearances throughout the Ghostbuster franchise, he was one of the ghosts to make a cameo appearance on the second opening theme song and even made an appearance on the Extreme Ghostbusters theme song and end song (though never appeared in any actual episodes). He also made numerous cameo appearances throughout the show. Samhain has also appeared in the Now Ghostbusters Comics in two comics, and made reference to in another.