Roy is both a given name and a family surname with varied origins.
Coat of arms of Le Roy, Normandy. Bibliothèque nationale de France.
"Roy" Edward III, King of England. Bruges Garter Book.
A given name is the part of a personal name that identifies a person, possibly with one or more middle names as well, and differentiates that person from the other members of a group who have a common
Roy
…Roy is both a given name and a family surname with varied origins. A furore Normanorum, libera nos, Domine! THE KING OF AMIGNY ... It is therefore to the seventh century that…
First/given/forename, middle, and last/family/surname with Edgar Allan Poe as example. This shows a structure typical for Anglophonic cultures (and some others). Other cultures use other structures for full names.
The sarcophagus at Riddarholm Church in Sweden of Queen Desideria, an official name given to Désirée Clary not at birth but when she became Crown Princess of Sweden in 1810.
American musician Prince became mononymously known by his birth name before later changing his stage name to an unpronounceable symbol.