Agent Fox Mulder, an Oxford-trained psychologist with a photographic memory, is one of the FBI Violent Crimes division's best agents, although he is in disfavor with not only his superiors but also his colleagues because of his interest in the Bureau's X files. He stumbled upon these files, dealing with unexplained phenomena, during his first three years with the Bureau, as a crack analyst in the Bureau's behavioral sciences department.

His fascination with the paranormal stems from a childhood incident -- his sister Samantha disappeared from their home in Chilmark, Mass. When he was 12 and she was 8. Mulder claims she was abducted by aliens; during regressions he recalled hearing his sister's cries for help, and a bright light which kept him paralyzed and told him that his sister would be all right.

Mulder's early meteoric rise at the Bureau has enabled him to make high-placed friends in Congress. These contacts keep him from retribution from higher-ups, although they have assigned him a partner, with the tacit idea of discrediting what he does so that he can be dismissed. However, Mulder picked up a somewhat vacillating ally in a mysterious covert individual known as Deep Throat.

Mulder is known around the Bureau by the nickname of "Spooky" because of his interest in paranormal phenomena. "He is considered a loose cannon, a person who is maybe wasting time and money, and also his expertise, on an area the Bureau thinks has very little value." Due to an incident on one of his first Bureau assignments (a fellow agent was killed) , he eschews following investigations "by the book," opting isntead for his own instincts and methods. He keeps notes for his field reports in a handwritten journal.

We believe Mulder doesn't "have a life," as we have seen nothing of his off-duty activities. However, some of this may stem from a relationship he had at Oxford ten years ago with a woman who is now with Scotland Yard. He apparently was in love with her, but she not with him.

Mulder has a fear of fire, which may have been conquered during his rescue of the children of British MP Sir Malcolm Marsden. He is also a fan of the National Aeronautics and Space Administration (NASA). He has a habit of unshelling shelled sunflower seeds, and making droll comments which X-Philes have come to note as "Mulderisms."

Mulder enjoys wearing wild ties to work, and seems to be a New York Knicks fan. He appears to had a fondness for classic rock and classic science fiction movies, and iced tea seems to be his beverage of choice. There are "hints" that Mulder has an interest in pornography -- in one episode, we see Mulder looking at the centerfold of some "men's magazine" talking about how the woman claims she was abducted by aliens; in another episode Scully remarks that she hadn't seen Mulder that excited since she caught him going through the Adult Video News. As a psychologist, he favors using hypnotic regression as a psychological healing tool, and hates the unnecessaryuse of medication.