Ian Detweiler
Ian Detweiller was a cryptozoologist who tracked and caught a wanshang dhole in China in 1999. However, he was somehow transformed into the creature himself. He attempted to hide his condition but would morph into the wolf-like being each night and viciously killed a number of victims after arriving in the United States aboard the T'ien Kou. Mulder and Scully were tracking the creature with Detwiler's supposed aid, but figured out his true identity with help from Karin Berquist. He was killed while attempting to kill Berquist when he lunged at her, throwing both out of a window. Detweiler was impaled on a post below.