Xer·xes I 
(zûrksēz) Known as "Xerxes the Great." 519?-465 BC.
(zûrksēz) Known as "Xerxes the Great." 519?-465 BC. King of Persia (486-465) who organized a vast army that defeated the Greeks at Thermopylae and sacked Athens (480). After the defeat of his navy at Salamis (480) and of his army at Plataea (479), he retreated to Persia, where he was later assassinated.