Belshazzar ( /bɛlˈʃæzər/; Biblical Hebrew בלשאצר; Akkadian: Bēl-šarra-uṣur), sometimes called Balthazar (/ˈbælθəˌzɑr/), was a 6th century BC prince of Babylon, the son of Nabonidus and the last king of Babylon according to the Book of Daniel in the Hebrew Bible. In Daniel 5 and 8, Belshazzar is the King of Babylon before the advent of the Medes and Persians. Although there is evidence that Belshazzar existed, his famous narrative and its details are only recorded in the Book of Daniel, which tells the story of Belshazzar seeing the writing on the wall.
Belshazzar was the son of Nabonidus, who after ruling only three years, went to the oasis of Tayma and devoted himself to the worship of the moon god Sin. He made Belshazzar co-regent in 553 BC, leaving him in charge of Babylon's defense. In 540 BC, Nabonidus returned from Tayma, hoping to defend his kingdom from the Persians who were planning to advance on Babylon. Belshazzar was positioned in the city of Babylon to hold the capital, while Nabonidus marched his troops north to meet Cyrus. On October 10, 539 BC, Nabonidus surrendered and fled from Cyrus. Two days later the Persian armies overthrew the city of Babylon.