Nabonidus (
năbənī'dəs), d. 538? B.C., last king of the Chaldaean dynasty of Babylonia. He was not of
Nebuchadnezzar's family, and it is possible that he usurped the throne. He was absorbed in antiquarian and religious speculations, and he built temples while the state was left undefended. He was unpopular with both the priests and the people. When the Persian threat of
Cyrus the Great grew strong, Nabonidus allied himself with
Croesus of Lydia and
Amasis II of Egypt, but to no avail. In 538 B.C. the kingdom fell to Cyrus with no resistance. Nabonidus' scholars preserved information valuable to modern archaeologists. Cuneiform records indicate that
Belshazzar was Nabonidus' son and his coregent during the last years of Babylon.