Who is Bessus from The Campaigns of Alexander and what is their importance?

Bessus was a member of the Persian army. After the Persian defeat at the Tigris River, Bessus left the field with Darius to escape from Alexander. He killed Darius as Alexander neared, in the hope that Alexander would not kill him. Alexander, however, presses on to capture Bessus after hearing that he has declared himself the new ruler of Persia. When Alexander catches Bessus, he whips him, cuts off his nose and ear tips, and sends him away to be executed.