'Balthasar' originates from Akkadian, specifically the word 'Bel-šar-uṣur', where 'Bel' meant 'lord' (a Babylonian deity) and 'šar-uṣur' meant 'protect the king'.

'Balthasar' changed from the Akkadian/Babylonian form 'Bel-šar-uṣur' into Greek and Latin biblical and medieval forms such as 'Balthazar'/'Balthasar' and eventually became the modern English name 'Balthasar'.

Initially it meant 'Bel protects the king' (a theophoric personal name), but over time it evolved into a proper personal name associated especially with one of the Magi and now functions as a given name or literary name.