Eustathios Argyros (Greek: Εύστάθιος Άργυρός) was a Byzantine admiral under Emperor Leo VI the Wise (r. 886–912).
At the time, he was already patrikios and commander of the imperial fleet (droungarios tou ploimou), and he was sent to the Danube to ferry across the allied Magyars and put pressure on Bulgaria from the rear; the strategy worked, and Tsar Simeon asked for peace.
[1][2][3] In 902, Emperor Leo VI the Wise had sent a fleet under Eustathios to aid Taormina in Sicily, which was being threatened by the Arabs.
Modern scholars assume that the fleet's departure was fatally delayed, perhaps, as Theophanes Continuatus claims, because the emperor himself employed its sailors in church construction.
Leo replaced him with Himerios, but he too was unable to effectively oppose the Saracens, who went on to sack the Empire's second city, Thessalonica.