Mulder as he appears on The X Files
|Occupation||FBI Special Agent|
|Family||C.G.B Spender (father)|
Samantha Mulder (Sister)
|Appearances on The Simpsons||The Springfield Files|
|Portrayed and voiced by||David Duchovny|
|Enemies||Cigarette Smoking Man|
Fox Mulder, at an early age, got a dislike of insects and fire, when his friend's house burned down. He also had an interest in science-fiction, something which would carry over to his adult years. Fox was scarred for life when his sister Samantha suddenly disappeared. One of his reasons to join the X-Files was to find out what happened to her. During a session of hypnotic regression, he discovered that she was abducted by aliens, but even Mulder has doubts over if it was real.
 The X-Files
Fox started the X-Files with a female partner before she left and was replaced with Dana Scully. Scully was partnered with Fox so that she could apply her scientific learning to the cases, although because most of their cases were paranormal, her scientific reasoning was rarely applied. Their first case was on various classmates that graduated at the same school in the same year who disappeared and suddenly reappeared dead. He eventually starts to believe that the government is hiding several secrets.
Mulder usually believes in the supernatural in the X-file cases while Scully remains a sceptic, although in a small amount of episodes the role was reversed.
 Samantha Mulder
His other main goal was to find out what happened to Samantha. In the 7th season, it was revealed that Samantha was indeed abducted and was sent to live with the Cigarette Smoking Man. She escaped and went to the nearest hospital, where she died from supernatural means.
 Appearance in the Simpsons
In the Simpsons episode The Springfield Files, Mulder and Scully were in the FBI building in Mulder's room when Mulder reads Homer Simpson's alleged alien sighting. They were sent to Springfield to investigate Homer's sighting in a forest. Mulder and Scully ask Homer various questions, during which Homer gets drunk. Moe asks who they were and after Mulder responds that they were FBI, Moe alerts several people in a back room who were with a whale to get him back to Sea World. The trio go back to the forest only to find Abe Simpson, who was lost in the forest chasing a turtle who had managed to steal his false teeth. After Abe got bitten by the turtle, Scully replys that the case was irritating and decides to leave. Mulder, meanwhile stays with Homer and starts a speech on the paranormal, finishing with "The truth is out there!" Immediately after, Mulder and Homer witness Moe still attempting to take the whale to Sea World by carrying it.
Mulder and Scully both return at the end of the episode to sing 'Good Morning Starshine' with the Springfield residents.