Which Spartan king succeeded Leonidas I after the Battle of Thermopylae?

Pleistarchus succeeded Leonidas I as king of Sparta after the Battle of Thermopylae.

Pleistarchus belonged to Sparta’s Agiad dynasty and was the son of Leonidas I and Gorgo. He was still a child when Leonidas died at Thermopylae in 480 BCE, so the regent Pausanias exercised authority on his behalf. Pleistarchus remained king until his death, but he left no surviving son.

Because Sparta had two hereditary kings, Pleistarchus ruled alongside a king from the Eurypontid dynasty. This dual monarchy was unusual among Greek city-states, although the kings’ practical authority was balanced by the ephors, the Gerousia, and the assembly.

Pleistarchus is less famous than his father because he did not command the celebrated defense at Thermopylae. The battle made Leonidas an enduring symbol, while Pleistarchus’ reign illustrates how Spartan kingship could continue through a child king and a regent.