Surt  is the destroyer, a godlike ghost who sought to bring about Ragnarok, the end of the world.
According to Egon Spengler, in Norse mythology, Surt brings about the destruction of the world after his minion Fenris prepares his coming by enslaving three human souls.  The original Ghostbusters and Slimer somehow trapped Surt years ago in an undisclosed bust.  He was remanded to the Containment Unit where he built up an army of other entities. Like the others, Surt believed one day he would exact his revenge on Slimer, a traitor from his point of view. In 1997, Surt added the Glostic Sisters, Banshee and Siren to his army. It appears they resisted at first but Surt bound them by chains and punished them for their impudence.
Some time after the Glostic Sisters and Lotan were placed in the Containment Unit, Surt was presented with Slimer. After sensing Eduardo Rivera's presence, he forced Siren to hypnotize Slimer and bend the ghost to Surt's will. Then he allowed Eduardo to reunite with Slimer in anticipation that Eduardo would open the exit to the Containment Unit. Surt would then trigger Slimer to attack Eduardo while he escaped and fulfilled the apocalyptic prophecy he is attached to. Just as Surt was about to escape, Kylie Griffin wrangled Fenris with her Proton Pistol and shoved him into Surt. Since Fenris represented ice and Surt represented fire, the collision of opposites was enough to force the two entities back behind the inner hatch.  The Containment Unit was then resealed.
Surt desires to cause Ragnarok and has power over even the mightiest of ghosts, to the extent that he used Siren to control Slimer.
Surt has the power of pyrokinesis and remote viewing. He also has the ability to command lesser entities but it is unclear if this is a telepathic power or just his personality that draws them.
- On page 19 of Ghostbusters Volume 2 Issue #6, Surt makes a non-canon cameo on a photo on a board in the lower right corner of last panel. The photo is based on Tobin's Spirit Guide fan art done by Tristan Jones.
- Egon Spengler (1997). Extreme Ghostbusters- Slimer's Sacrifice (1997) (DVD ts. 04:05-04:15). Sony Pictures Home Entertainment. Egon says: "He's what you might call the point man for the apocalypse. According to Norse mythology, Fenris prepares the way for Surt, who in turn brings about the destruction of the entire world."
- Egon Spengler (1997). Extreme Ghostbusters- Slimer's Sacrifice (1997) (DVD ts. 06:40-06:46). Sony Pictures Home Entertainment. Egon says: "According to legend, he must enslave three souls in order to fulfill the apocalyptic prophecy."
- Egon Spengler (1997). Extreme Ghostbusters- Slimer's Sacrifice (1997) (DVD ts. 04:22-04:26). Sony Pictures Home Entertainment. Egon says: "Fenris' master could never fulfill his mission. We captured Surt years ago."
- Kylie Griffin (1997). Extreme Ghostbusters- Slimer's Sacrifice (1997) (DVD ts. 20:03-20:08). Sony Pictures Home Entertainment. Kylie says: "Fire and ice. Some opposites cancel each other out on contact. Others just explode. Either way, they lose."