Greg Pincus is the main antagonist of the X-Files episode "Folie à Deux".
Greg Pincus disguised himself as the CEO of the VinylRight Corporation but was, in truth, a giant insect that infected his workers one by one, turning them into zombies. His reasons for doing so remain dubious. Gary Lambert, one of his employees, found out the truth and held Pincus and his zombie's hostage one afternoon, demanding to be broadcast on TV so he could show the people of the world that a monster walked among them.
Mulder arrived at the building to talk to Pincus but was held at gunpoint. With Scully's help, the FBI was able to enter the building and kill Lambert, who did not kill Pincus or show the world his boss' true identity, but did show Mulder 'the monster.' Mulder gathered evidence by stalking Pincus' zombies, who testified against Mulder, telling Skinner he had a 'madman' FBI agent.
Mulder was taken to a hospital and strapped to a bed by a zombified nurse, who opened the window after Mulder specifically told her not to do so. Pincus entered, crawled over the ceiling and was about to infect Mulder when Scully burst in, shot Pincus twice before he fled out the window. When reporting to Skinner, Scully stated that she remained skeptical of the whole incident, but was adamant there was an intruder in Mulder's room. Pincus remained at large and would move to another VinylRight office, this time killing the man who could see him prevent another incident.