What is the name of the mountain near Thermopylae that overlooks the pass?

The mountain near Thermopylae that overlooks the pass is Mount Kallidromon, also written Kallidromo or Kallidromos. The mountain rises south of the historic route, which in antiquity ran between its steep slopes and the Malian Gulf.

Kallidromon was more than background scenery in the Battle of Thermopylae. A mountain path known as the Anopaea or Anopaia route crossed its slopes. In 480 BC, a local Greek named Ephialtes showed the Persians this path, allowing troops under Hydarnes to move around the main Greek position and attack from the rear.

That maneuver made the narrow coastal pass untenable. Once Leonidas learned that the Persians were approaching through the mountain route, he dismissed most of the allied army and stayed behind with a rearguard, including Spartans and Thespians. The mountain is therefore directly connected to the battle's decisive turning point.

The landscape has changed substantially since antiquity. Sediment from the Spercheios River has pushed the shoreline outward, making modern Thermopylae much wider than the ancient pass. Kallidromon remains the distinctive mountain barrier associated with the site.