Granny Gross is a ghost that poses as a senior citizen.
While the Ghostbusters' Interspatial Teleportation Unit was in use, the energy put out by the interdimensional portal attracted the Granny Gross ghost. She entered the portal and arrived in the basement of the Firehouse. She immediately started smelling the air. Special Agent Melanie Ortiz mistook her for an actual person and tried to talk to her until she transmogrified. Jenny Moran was overcome by her rancid breath. Melanie volunteered to distract the ghost while Jenny and Kylie Griffin ran for the stairs and grabbed some equipment upstairs. Melanie ran at high speed and tackled the ghost in the throat which severed her head. The ghost grabbed its floating head and reattached it. Melanie taunted the ghost until it lunged at her. Peter Venkman and Winston Zeddemore trapped it as they crossed over from a parallel dimension occupied by a team of Ghostbusters they recently met. The Egon Spengler of that dimension came with them and remarked the Granny Gross ghost looked familiar.
Granny Gross can conceal its true form and take on the appearance of an innocent elderly woman. In offensive mode, she can extend the length of her jaw to the extreme. She also demonstrated the ability to reassemble herself after her head was separated from her body.
- The ghost is visually based on Kenner's The Real Ghostbusters Haunted Humans: Granny Gross Ghost figure.