Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.
ROY
As described in historical dictionaries
An Etymological Dictionary of Family and Christian Names (1857)
(origin: Gaelic.) Ruadh, Roe, Roy, red-haired; also Roye, a town in England. Roi, French, king, whence Le Roy.
Patronymica Britannica (1860)
ROY. Has no relation to the Fr. roi. It is Gaelic, and signifies the red-haired ; and, as such, it has often been n.sed as a sobriquet, down almost to our own times, in conjunction with, or to supersede, a family name.
Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
Region of origin: Asia