From בֵּלְשַׁאצַּר (Belshatzzar), the Hebrew form of the Akkadian name Bel-sarra-usur meaning "BA'AL protect the king". This was the name of the son of Nabonidus, the last king of the Babylonian Empire before it was conquered by the Persians in the 6th century BC. In the Old Testament Book of Daniel Belshazzar is the last king of Babylon who sees the mystical handwriting on the wall, which is interpreted by Daniel to portend the end of the empire.