Originally a Scottish name, representing an Anglicized spelling of the Gaelic nickname Ruadh ‘red’. It has since spread to other parts of the English-speaking world, where it is often reanalysed as Old French roy ‘king’ (compare Leroy).
English and Welsh: patronymic from the Middle English personal name Jon(e) (see John). The surname is especially common in Wales and southern central England. In North America this name has absorbed various cognate and like-sounding surnames from other languages. (For forms, see Hanks and Hodges 1988).