Guy Fawkes is the reason for a word which is called "guys", a generic term for men.
The term actually comes from Guy Fawkes, a 17th-century participant in the failed 1605 Gunpowder Plot (and the inspiration behind those creepy, mustachioed, "V for Vendetta" masks that Anonymous wears).
Fawkes was a Catholic during a time of great religious conflict and persecution in England. He was also a member of a group of thirteen conspirators who wanted to restore a Catholic monarch to the throne. Their idea was to blow up Parliament with barrels of gunpowder in order to kill the Protestant King James I, the Privy Council, and the bishops of the Church of England.
Fawkes was not the leader of the group. He's remembered because on November 5, 1605, he got caught in the basement of Parliament with enough gunpowder to level the building (authorities had been searching the building after receiving an anonymous tip).
Things ended pretty badly for Fawkes. He was most likely horrifically tortured on the rack. He managed to escape a grisly execution by jumping off the scaffold and breaking his neck. For centuries, England has celebrated the foiling of the plot by burning effigies of Fawkes and other figures on November 5. Those likenesses became known as "guys." According to the Boston Globe, the term morphed into a way to describe creepy people. Over time, it became a generic term for men, although today it is often used as a gender-neutral phrase.