"The Iron Maiden" is a nickname that students at the FBI Academy used for forensics instructor Nancy Spiller.
When Agent Jerry Lamana mentioned Spiller to Special Agents Fox Mulder and Dana Scully in 1993, Scully recalled that she and other students had routinely referred to Spiller by her nickname. Replying to Scully, Jerry Lamana not only implied that he had also used the nickname for Spiller but also light-heartedly recalled that, despite its serious connotations, the nickname had only been used "on a good day." (TXF: "Ghost in the Machine")