At an unspecified point in time, the Ghostbusters fought the Old One and stopped it from destroying the world.  It went into hiding underground and waited for its next opportunity.
Vladimir Pavel Maximov and his assistant Dmitri Smerdyakov planned to summon an Old One using The Nameless Book.  Vladimir was promised by the Old One he would become ruler of Earth.  In order to keep the visiting Ghostbusters from interfering, they stole the book from a Soviet institute, and blamed the Ghostbusters. Meanwhile, Vladimir and Dmitri met up with an Old One Cult miles outside of Dnepropetrovsk to summon the Old One from a secret underground temple thousands of years old.
Fortunately, the Ghostbusters made it to the Old One's lair and were able to stop it before it completely made it to the surface. Slimer was sent back home to get "Big Trouble", a huge apparatus that uses the power of all the Proton Packs to create a rip in space-time, like a black hole, to absorb everything it touches. Peter Venkman bravely threw Big Trouble into the pit and ran way as he saw the Old One revealed its hideous form. Big Trouble activated and sent the Old One back to where it belonged.
- ↑ Ray Stantz (2009). The Real Ghostbusters - "Russian About" (1990) (DVD ts. 08:01-08:05). Time Life Entertainment. Ray says: "It's sort of a leftover from a time when these creatures called the Old Ones ruled the Earth."
- ↑ Egon Spengler (2009). The Real Ghostbusters - "Russian About" (1990) (DVD ts. 08:06-08:11). Time Life Entertainment. Egon says: "Supposedly, there's one Old One left. We fought him before. He almost destroyed the world."
- ↑ Egon Spengler (2009). The Real Ghostbusters - "Russian About" (1990) (DVD ts. 08:12-08:14). Time Life Entertainment. Egon says: "Only two books can wake him up. That's one of them."
- ↑ Vladimir Pavel Maximov (2009). The Real Ghostbusters - "Russian About" (1990) (DVD ts. 19:11-19:14). Time Life Entertainment. Vladimir says: "He made promise I would rule the world."