The Harasvelg (also known as Hraesvelgr, Hrae-Svelger, Hraesvelg, or Hraesvelgur) is a giant winged creature from Norse mythology. It has a very nasty disposition toward humans and flies around terrorizing anyone below.
In the past, the Harasvelg was summon by the Scandinavian tribes to fight against their enemies with the usage of a relic called the Sceptre of Donar. However, it proved too difficult to control and eventually turned against the Scandinavians themselves, causing unbelievable devastation and destruction. The Scandinavians swore to never call upon it again for the next hundreds of years.
In 1997, the Sceptre was found and donated to a museum in New York City. A boy named Sven Christianson (who is a Scandinavian descendant) broke into the museum in hopes of using the sceptre of summoning the Harasvelg. Though Sven succeeded in summoning the beast, he is horrified to see that the Harasvelg is wreaking havoc by causing sudden swings in temperature and weather.
Horrified of what he has done, Sven turned over to the Ghostbusters, who decided to lure the Harasvelg into Battery Park in hopes to trapping it. Using the Sceptre, the Ghostbusters used their Proton Packs to fire at the Scepter, weakening the Harasvelg and allowing the Ghostbusters to trap it with a Ghost Trap for good. Unfortunately, before the Harasvelg was captured, it created a tornado that was impossible to stop because of the heat feeding it. Fortunately, Slimer used one of the Proton Packs to dissipate the tornado, fully ending the Harasvelg's reign of terror for good.