Roy

From various sources:

Anglo-Norman roy (“king”) a variant of Old French roi, from Latin rēx, rēgem from Proto-Indo-European *h₃rḗǵs (“ruler, king”). Doublet of Rey.

Scottish Gaelic ruadh (“red, red-haired”) from Old Irish rúad, from Proto-Celtic *roudos from Proto-Indo-European *h₁rewdʰ-.

Anglicisation of Bengali রায় (raẏ, surname). Doublet of Rai, rex, and rajah.