What is the name of Fox Mulder's sister who was abducted?

Fox Mulder’s abducted sister is named Samantha Mulder. Her disappearance is the central personal mystery that drives Mulder’s obsession with extraterrestrials and unexplained phenomena.

According to the series’ backstory, Samantha was taken from the Mulder family home on Martha’s Vineyard on November 27, 1973. Fox was 12 years old and remembered witnessing the event, although later revelations complicated whether every detail of his memory was accurate. The case led him toward the FBI’s X-Files and shaped much of his career.

The series repeatedly introduced apparent versions of Samantha, including clones and impostors, which created deliberate confusion for both Mulder and viewers. Her storyline develops through episodes such as “Conduit,” “Colony,” “Paper Hearts,” and “Closure.” The seventh-season episode “Closure” provides the emotional resolution to her story.

Diana Fowley is an FBI agent connected to Mulder, while Melissa Scully is Dana Scully’s sister. Neither is related to Mulder. Samantha’s disappearance is therefore not just a family detail; it is the emotional foundation of The X-Files’ long-running mythology.