1. King of Sparta, of the line of the Agids, was the son and successor of the heroic Leonidas, who was killedin at Thermopylae, B. C. 489.
He was a mere child at the time of his father's death, on which account the regency was assumed by his cousin Pausanias, who commanded the Greeks at Plataea. (Hdt. 9.10
; Paus. 3.4.9
It appears that the latter continued to administer affairs in the name of the young king till his own death, about B. C. 467 (Thuc. 1.132
). Whether Pleistarchus was then of age to take the reins of government into his own hands we know not, but Pausanias tells us that he died shortly after assuming the sovereignty, while it appears, from the date assigned by Diodorus to the reign of his successor Pleistoanax, that his death could not have taken place till the year B. C. 458. (Paus. 3.5.1
; Diod. 13.75
; Clinton, F. H.
vol. ii. p. 210.) No particulars of his reign are recorded to us.