Donald "Donnie" Pfaster is an antagonist in the X-Files episodes "Irresistible" and "Orison". He was played by Nick Chinlund.
Donnie Pfaster is a serial killer, also labeled as a "death fetishist", who prays upon young women and has a special fixation towards blondes. He also likes to collect hair and nails from his victims as trophies. Formerly working at a funeral home, Pfaster was eventually fired when his fetish was discovered by his superior. Pfaster's fetish began with mere grave robbing but gradually developed into a string of murders.
In Season 2, agents Mulder and Scully investigate a case where Pfaster has brutally murdered a young prostitute. The case becomes especially emotional for Scully, as she fits the profile for Pfaster's victims. Pfaster eventually notices Scully when she and Mulder interrogate a suspect. He then kidnaps her by driving her car off the road and holds her captive in his mother's house. Scully manages to hold back until the FBI comes to her aid. Pfaster is then arrested and sent to prison for his crimes.
This is not the end of Pfaster however, since he was deliberately released from prison in 2000 among other inmates by Robert Gailen Orison so he could murder them himself. Pfaster manages to escape and continues his string of murders. He then makes his way to Scully's apartment in Washington where he attacks her but is shot to death by Scully before Mulder manages to arrest him.