Leonidas I is the legendary Spartan king shown fighting at Thermopylae in Assassin's Creed Odyssey.
The game opens with a playable prologue in 480 BCE, placing Leonidas and his Spartan warriors at the Battle of Thermopylae. This historical sequence establishes the family and political background for the later story, which is set during the Peloponnesian War.
Leonidas was a real king of Sparta from the Agiad dynasty. Ancient accounts, especially those associated with Herodotus, describe his command of the Greek force at the narrow pass of Thermopylae against the invading Persian army. The game dramatizes the event while connecting it to its fictional protagonist and mythology.
Pericles and Miltiades were also real Greek figures, but neither was the Spartan king depicted in the Thermopylae prologue. Philip II belonged to Macedon and lived in a different period.