Who is the cancer man from x files?

During the first mytharc fifth season episodes, the Elder has decided that CSM is no longer useful, and orders MIB operative Quiet Willy to eliminate him. While in his apartment, CSM was ruminating over a photograph of Mulder and Samantha when an assassin firing through the window shot him in the chest. During this episode he also helps Mulder find a cure for Scully's cancer (which she learned about in season 4), and presents him with a Samantha clone, whom he purports is Mulder's sister. Despite this, Mulder refuses to work for him. CSM later appears hiding in a remote area of Quebec. Missing his talents, the Syndicate welcomes him back at the end of the season.