Mulder believes in UFOs and in a government conspiracy to hide or deny the truth of their existence. He and Dana Scully work in the X-Files office, which is concerned with cases with of a particularly mysterious—or possibly supernatural—nature that were left unsolved and shelved by the FBI.
When Homer believes he has seen an alien, Mulder and Scully come to Springfield to investigate. They interview Homer, put him through a series of medical tests, and eventually determine that Homer was crazy. Mulder then stays in the forest, talking alone about the mysteries of the universe until night (which also resulted in a brief run-in with Moe and two men trying to haul an orca all the way back to SeaWorld). Their attempts to interview the populace of Springfield, particularly Moe Szyslak of Moe's Tavern, also got Moe spooked, especially when he learned that Mulder was a member of the FBI (due to his storing the aforementioned orca behind the tavern that he presumably stole from SeaWorld).
Behind the laughter
- Fox Mulder is one of the main characters from the drama series The X-Files.
- The picture Mulder has, in his wallet, of him in black underwear, is a reference to "The Red Shoe Diaries", which also starred Fox Mulder actor, and voice actor, David Duchovny. It may also be a reference to "Duane Barry", an X-Files episode where Mulder is seen, in a red speedo.
- Episode – "The Springfield Files"
- Episode – "Missionary: Impossible" (cameo)
- Episode – "Springfield Splendor" (photo at Springfield Sardi's)
- Comic story – I Faced Tahn-Enn-Bahm, The Christmas Tree From Another World
- Comic story – The Ex Files
- Book – Comic Book Guy's Book of Pop Culture
- Book – Simpsons World: The Ultimate Episode Guide, Seasons 1-20
- Special – "FOX's 25th Anniversary Special"