Yes, Leonidas deserves the credit, but I'm a fan of Demophilus.
"When Leonidas learned that the Phocians had not held, he called a council at dawn. During the council some Greeks argued for withdrawal in the face of the overwhelming Persian advance, while others pledged to stay. After the council, many of the Greek forces did choose to withdraw. Herodotus believed that Leonidas blessed their departure with an order, but he also offered the alternate point of view: that those retreating forces departed without orders. The Spartans had pledged themselves to fight to the death, while the Thebans were held as hostage against their will. However, a contingent of about 700 Thespians, led by general Demophilus, the son of Diadromes, refused to leave with the other Greeks, but cast their lot with the Spartans."
In the history and the legend of Thermopylae, nothing can be taken away from the Spartans. By custom, by training, by law, by loyalty and a great leader, the royal guard of King Leonidas fulfilled their heroic destiny at the Battle of Thermopylae. But Demophilus was no Spartan, no warrior born and bred from the womb. He was a Thespian general and he led 700 volunteers of his countrymen alongside his fellow Greeks against the overwhelming army of Xerxes I. He easily could have retired from the field of battle with the other Greeks when the Spartans made their last stand, in what was possibly a designed rear-guard action. He didn't. The Thespians stayed, shoulder to shoulder with the Spartans, as equals, as brothers, as Men. Demophilus understood this act was necessary for the greater good, and it would mean the sacrifice of his soldiers and himself. He died in battle, and in so doing, he and his Thespians have shared for all time, with the great Spartan warriors, the honor of the Battle of Thermopylae.
We all die - there's no choice about that. Normally, I would wish for a long, happy, and fruitful life ending, if it must end, in a painless death. However, I can't help but believe some deaths are more worthy than others, that there is such a thing as a good death. At the end, Demophilus earned a heroic death, a Spartan's death, that wasn't his by birthright. I'm no warrior and I can't identify with the Spartans. But I can hope that when the moment of clarity arrives, I'll acquit myself as honorably as Demophilus the Thespian at Thermopylae.
** Post was inspired by reading Frank Miller's graphic novel, 300.