What famous character did William B. Davis portray?

William B. Davis, a Canadian actor, portrayed the Cigarette Smoking Man on the popular sci-fi show, "The X-Files." The Cigarette Smoking Man, also known as CSM and C.G.B. Spender, was an antagonist responsible for many global conspiracies surrounding the existence of extraterrestrial life. He is also the biological father of Special Agent Fox Mulder, Special Agent Jeffrey Spender, and Jackson Van De Kamp (also known as William Scully III).