Darius III (the Great) (ca.

380–330 BCE), also known by his given name of Codomannus, is the last king of the Achaemenid Empire of Persia from 336 BCE to 330 BCE.

After Artaxerxes III of Persia and all of his sons are killed by the vizier Bagoas, the vizier instals a cousin of Artaxerxes III, Codomannus, to the Persian throne as Darius III.

When Darius tries to act independently of the vizier, Bagoas tries to poison him, but Darius is warned and forces Bagoas to drink the poison himself.

The new king finds himself in control of an unstable empire, large portions of which are governed by jealous and unreliable satraps and inhabited by disaffected and rebellious subjects.

However, he lacks the skills and experience to deal with these problems.

In 334 BCE, Alexander the Great begins his invasion of the Persian Empire and subsequently defeats the Persians in a number of battles before looting and destroying the capital Persepolis, by fire, in 331 BCE.

With the Persian Empire now effectively under Alexander's control, Alexander then decides to pursue Darius, but Darius is killed by a satrap Bessus before Alexander reaches him.