"small rope, chain, wire," 1620s, nautical; earlier "leader" (mid-14c.), from Old French guie "a guide," also "a crane, derrick," from guier, from Frankish *witan "show the way" or a similar Germanic source, from Proto-Germanic *witanan "to look after, guard, ascribe to, reproach" (source also of German weisen "to show, point out," Old English witan "to reproach," wite "fine, penalty"), from PIE root *weid- "to see." Or from a related word in North Sea Germanic.
"fellow," 1847, American English; earlier, in British English (1836) "grotesquely or poorly dressed person," originally (1806) "effigy of Guy Fawkes," leader of the Gunpowder Plot to blow up British king and Parliament (Nov. 5, 1605). The effigies were paraded through the streets by children on the anniversary of the conspiracy. The male proper name is from French, related to Italian Guido.