Big Green, sometimes known as Ectoplasmic Parasitic Mutation, is an evil doppelgänger of Slimer.Voiced By Slimer's Alyssa Milano
There was a leak in the Containment Unit As a result, a small amount of ectoplasm escaped but not enough to constitute a whole ghost. The ectoplasm was some form of catalytic paranormal flux, harmless to corporeal entities but to incorporeal ones, the flux could induce malevolent ectoplasmic metamorphosis. It changes small, friendly ghosts into big, scary ones.The energy leak infected Slimer while he slept. Thus, Slimer would sleep walk, in a sense, and transform into a monster form without knowing it. The monster carried out his base desire, to eat everything.
The Ghostbusters first encountered the monster at a 24 hour deli where it was dubbed "Big Green." They met it again at Neptune's Floating Restaurant where they tried to use Plan 52-A but failed to trap it again. While checking the Containment Unit, the Ghostbusters were attacked by Big Green. They trapped it but tripped on his ectoplasm and released him, only to find Slimer. Egon deduced the energy leak infected Slimer. Ray added the transformations only happen when Slimer slept. Egon discovered worse news. If Slimer transformed enough times, he would be stuck as Big Green. Slimer was terrified and clung tightly to Peter. While Egon and Ray consulted books to find a cure, Peter and Winston worked to keep Slimer awake. They tried to make eat his favorite junk food in the kitchen but he began to fall asleep. Winston grabbed the radio and set it to full blast then he and Peter danced to the tunes. That didn't work either. Winston got another idea and scared Slimer awake. Winston left the dining table to check on Egon and Ray. Egon was at his wit's end and declared there was no way to reverse Slimer's condition. They soon heard Peter's scream.
Slimer had transformed again and cornered Peter in the kitchen. The others arrived and opened fire but Big Green flew through the window. Ecto-1 soon departed in pursuit. The guys entered a City Supermarket and found Big Green's slime everywhere. When it was suggested they split up in pairs, Egon got an idea. They could induce ectoplasmic fission with the throwers. Egon instructed everyone to set their thrower to 50,000 Giga Hertz. They sneaked up on Big Green but he turned and slimed Peter again. Peter bounced a Proton Stream off a mirror and nailed Big Green. The recoil launched the guys into the fruit stands. But the direct hit was a success. Slimer was separated from Big Green. Slimer was freaked out and hid in an orange juice bottle. Winston got his attention and asked what he would eat in this supermarket above all else. Slimer took the guys to the frozen section for Popsicles. Sure enough, Big Green was in there. The guys opened fire and confined the ghost. Peter broke off and threw out his Trap.
Flashbacks of Big Green's appearance are seen in the hour-long version of the later episode "Deja Boo."
<img src="http://img1.wikia.nocookie.net/__cb20140929141940/villains/images/thumb/e/e0/Biggreen.png/338px-Biggreen.png" alt="Biggreen" class="thumbimage " data-image-key="Biggreen.png" data-image-name="Biggreen.png" width="338" height="259" >Big Green employs unique tactics to avoid the Proton Streams. It spins in a circle and can spin itself into a vortex and emit large amounts of ectoplasm.