According to the Hebrew Bible, Belshazzar is the King of Babylon mentioned in the Book of Daniel, chapters 5 and 8; he is identified as the son of Nebuchadnezzar and as the last king before the advent of the Medes and Persians.
The name appears also in Baruch i. 11 as "Balthasar" (R. V. "Baltasar"). The allusions to this person in Baruch and elsewhere in extracanonical literature are all based on the data given by Dan. v. and viii.
It is stated in Dan. v. that Belshazzar gave a banquet to the lords and ladies of his court. In this court the sacred vessels of the Temple in Jerusalem, which had been brought to Babylon by Nebuchadnezzar at the time of the Judean captivity in 586 B.C., were profaned by the ribald company. In consequence of this, during the festivities, a hand was seen writing on the wall of the chamber a mysterious sentence which defied all attempts at interpretation until the Hebrew sage Daniel was called in. According to the story, Daniel read and translated the unknown words, which proved to be a divine menace against the dissolute Belshazzar, whose kingdom was to be divided between the Medes and Persians. In the last verse we are told that Belshazzar was slain in that same night, and that his power passed to Darius the Mede
This event was followed immediately afterwards by the Persian conquest of Babylon. This Biblical story is the source of the popular phrase "the writing is on the wall" as an euphemism for doom, especially impending doom that is so obvious only a fool would not see it coming.