Eurysthenes (; c. 400 BC) was a descendant of the Spartan king Demaratus.
After his deposition in 491 BC, Demaratus had fled to Persia, where king Darius I made him ruler of the cities of Pergamon, Teuthrania and Halisarna. About a hundred years later Eurysthenes and his brother Procles reigned over the same cities; their joint rule is at least attested for the year 399 BC.