Morpheus  is a demon inhabiting the dream world but tried to take over the human realm.
Morpheus mastered the domain of dreams and decided to do the same with the physical plane. Doing so required more power to cross over. He took control of the body of popular radio show host Barry Sherman while he slept. Morpheus used Sherman's voice as a conduit to enter the dreams of millions of people at once when they heard him over the radio.  While the victims slept, ghostly single-eyed, cell-like beings called Somniwyrms appeared over them, feeding on the nightmares. The nightmares Morpheus created were so intense, his victims actually felt the pain and effects of them upon awakening. Medical physicians classified the bruising as fractures caused by abnormally strong muscle contractions which occurred during nocturnal seizures.
After Garrett Miller became a victim, he was sidelined. Kylie Griffin remained with him and tried to figure out the connection between the nightmares and the radio. Garrett was able to identify a recurring demon in everyone's dreams as Morpheus. He and Kylie deduced Morpheus' plan and proceeded to shut down the radio show. However, it was too late. Morpheus had already generated enough Somniwyrms which began gathering over the WKYR station's rooftop and combining into the Morpheus Vessel, a physical representation that Morpheus would inhabit when he crossed over.
The Extreme Ghostbusters tried to prevent this from happening but Morpheus' reality warping powers rendered their equipment useless. Finally, Roland Jackson allowed him to complete his body and crossover into the realm of humans. The reason he did so was that Morpheus would become completely ectoplasmic, thus capable of being trapped. With Morpheus captured, his hold on all of his victims was lifted, as shown when Eduardo Rivera regained his hair, and Barry Sherman was free of his control.
While in possession of Barry, Morpheus could enter the dreams of millions of people at once, more than he could alone by using Barry's voice as a conduit into their minds. His nightmares were so potent that the victims felt actual pain upon awakening. He also had the power to transmogrify and animate objects and deflect Proton Streams around himself.
In possession of Barry, Morpheus' P.K.E. reading was right off the scale. 
- Morpheus appears in all of his victim's dreams in some form (e.g. in Eduardo's dream, he appears as Kylie's boyfriend and in the dream of the mailman in the beginning, he appears as the boss), The dreams he conjured in his victims' minds also seemed to reflect on their greatest fears.
- Among his victims were the Ghostbusters
- Garrett dreamed of being a NBA all-star player.
- Eduardo, while having a dream about Kylie, dreamed he was going bald, and much to his horror when he woke up, he had truly lost his hair.
- Roland dreamed of messing up a presentation of his latest invention. He gushed water out of all his orifices.
- Egon Spengler dreamed of walking around in public naked.
- Janine Melnitz dreamed of being the only human left on the planet.
- ↑ Garrett Miller (1997). Extreme Ghostbusters- In Your Dreams (1997) (DVD ts. 10:04-10:13). Sony Pictures Home Entertainment. Garrett says: "That's him. Morpheus, he's a demon inhabiting the dream world. But it says he never enters the physical plane."
- ↑ Kylie Griffin (1997). Extreme Ghostbusters- In Your Dreams (1997) (DVD ts. 10:22-10:26). Sony Pictures Home Entertainment. Kylie says: "Maybe the demon's using Sherman's voice as a conduit into people's minds."
- ↑ Kylie Griffin (1997). Extreme Ghostbusters- In Your Dreams (1997) (DVD ts. 17:22-17:23). Sony Pictures Home Entertainment. Kylie says: "It's going right off the scale."