The common English word for a man that developed from Guy Fawkes’s name is “guy.” The word did not begin as an ordinary synonym for man: it first referred to an effigy of Fawkes burned during 5 November celebrations.
After the Gunpowder Plot failed in 1605, people marked the king’s escape with bonfires and, over time, figures representing Fawkes. By the early 19th century, “guy” had become a term for a strangely or poorly dressed person, reflecting the homemade clothes used for these effigies.
The word’s history has two layers that are easy to confuse. Guy was already an old masculine given name, related to Germanic names such as Wido and popularised in medieval England by the legend of Guy of Warwick. The modern common noun came from the Fawkes effigy tradition, not from the original name itself.
In modern English, “guy” commonly means a man and can also appear in the plural phrase “you guys,” which is often used for groups of any gender.