» For the Christian saint, see Saint Bessus. Bessus (died summer 329 BC) was a prominent Persian nobleman and satrap of Bactria, and later self-proclaimed king of Persia. According to classical sources, he killed his predecessor and relative, Darius III, after the Persian army had been defeated by Alexander the Great. In the Battle of Gaugamela (October 1 331 BC), in which Alexander defeated Darius III, Bessus commanded the left wing of the Persian army, chiefly composed by troops of his satrap… (More on Bessus)