title: Belshazzar
context: Belshazzar (/bɛlˈʃæzər/; Hebrew: בֵּלְשַׁאצַּר, Belshatsar, Greek: Βαλτάζαρ, Baltázar, from Akkadian: 𒂗𒈗𒋀, Bēl-šar-uṣur, meaning "Bel protect the king")[3] was the eldest son of Nabonidus, the last king of the Neo-Babylonian empire, and regent for his father during the latter's prolonged absence from the city, although he never assumed the titles or ritual functions of kingship.[4] He may have been killed when Babylon fell to the Persians in 539 BCE.[5]
question: Who was the last king of Babylon?
answers: Belshazzar