Xerxes I was the son of Darius I and reigned as King of Persia spanning 486–465 BCE during the Achaemenid dynasty. The Achaemenid Empire is probably best known as the Persian dynasty that was founded by Cyrus the Great.
The video snippet below is from the 2006 film 300, which is based on one of the major battles of the second Persian invasion of Greece, the Battle of Thermopylae, which took place in 480 BC. In this scene the Spartan king and military commander Leonidas meets Xerxes I. It goes without saying that the accuracy of cinematic reenactments of historical events should be taken with a grain of salt :
Xerxes I's military incursion into the Greek mainland was a continuation of his father Darius I's first Greek invasion, spanning 492 to 490 BC. During that campaign in 490 BC, in a particular military engagement known as the Battle of Marathon, the Persian army was defeated. Darius died while preparing for a second invasion, thus leaving the leadership of the campaign to his son Xerxes I.
The army fielded by Xerxes I, according to recent historical accounts, numbered over 60,000 combatants. According to other accounts this number was much higher. This was a very diverse force, consisting of Thracians, Jews, Babylonians, Egyptians, Greeks, Macedonians, and even 20,000 Arab camelry and Libyan charioteers!
Between 480–479 BC a number of Greek cities were laid siege to and many razed by this massive force. The Greek standing infantry and naval forces eventually provided such formidable resistance that Xerxes I retreated back to Persia with the remnants of his army. Thus this second invasion was ultimately considered unsuccessful, as the Persian forces retreated without leaving a garrison in the Greek mainland.