The Demon Invader is a powerful demonic entity that almost crossed over into New York City, circa 1959.
After a little over an hour, a demon tried to exit a hole in the fabric of time caused by the Ghostbusters' and Slimer's presence in the past on April 10, 1959. At the height of a battle between Ghost Invaders and Engine Company 93, a demon appeared. He resisted the torrent of water shot at him and tried to blow the firefighters and Ghostbusters off their feet. Luckily, Egon Spengler finished recharging a Trap and recreated the accident that transported the Ghostbusters to the past. The hole was sealed up and the demon was forced back in and plummeted in downward spiral.