BIBLIOGRAPHIA IRANICA: Darius III: The Last Great King. New book: Safaee, Yazdan. 2016. Darius III: The Last Great King. Tehran: Hamisheh, Pishinpažouh.
Darius III was the last king of the Persian empire, defeated by Alexander the Great. He appears in the Book of Daniel implicitly in 8:7, when the he-goat from the west (Alexander the Great) strikes down the ram with two horns (the Medo-Persian empire). Darius III may also be the unnamed fourth king of Persia in 11:2. Darius was not actually the fourth king in the series of Persian rulers; he was more like the eleventh (depending on whom you count), but the writer of Daniel seems to have been less than fully informed about such matters.