Final answer:
Xerxes I was the Persian king who fought the Spartans at Thermopylae, inspiring the movie "300." The brave stand of the Spartans at Thermopylae against the much larger Persian army inspired the Greeks to unite and continue the fight against the Persians.
Step-by-step explanation:
The person who had his hands full fighting Spartans at Thermopylae, which inspired the movie "300," was Xerxes I. Xerxes I was the Persian king who launched an invasion of Greece in 480 BCE, intending to avenge the previous defeat of the Persians by the Greeks. At Thermopylae, a small band of Spartan warriors, led by their king Leonidas, made a stand against the invading Persian army, successfully holding them off for several days before ultimately being defeated. The bravery and sacrifice of the Spartans inspired the Greeks to continue fighting and unite as allies against the Persians.