The Parallelogram Ghosts is a group of ghosts who inhabit the realm of the New Jersey Parallelogram.
Due to the nature of the New Jersey Parallelogram as an area of high psychic turbulence and cross rip convergence, the realm is a prime habitat for unique types of ghosts. They range from origami-inspired entities to half-eaten fish bones to ectozoophillic entities (i.e. a bird-like one and a scorpion-like one). When a victim of the Parallelogram is teleported, the ghosts are present and offer their own twisted welcome.
When Jim Venkman arrived in search of Dr. Mulch and his ship, two Origami ghosts followed him. Eventually, Jim fell into a hole that led to a dome-like structure. Armed with only a paddle, Jim tried in vain to scare off the ghosts. Luckily, the Ghostbusters found him and scared off the ghosts with Proton Streams. The battle weakened the structure of the dome and caused the entire Parallelogram to disperse. It appears likely the ghosts dispersed, as well.