(Ἀλέξανδρος), the tenth king of MACEDONIA, was the son of Amyntas I. When Megabazus sent to Macedonia, about B. C. 507, to demand earth and water, as a token of submission to Darius, Amyntas was still reigning. At a banquet given to the Persian envoys, the latter demanded the presence of the ladies of the court, and Amyntas, through fear of his guests, ordered them to attend. But when the Persians proceeded to offer indignities to them, Alexander caused them to retire, under pretence of arraying them more beautifully, and introduced in their stead some Macedonian youths, dressed in female attire, who slew the Persians. As the Persians did not return, Megabazus sent Bubares with some troops into Macedonia; but Alexander escaped the danger by giving his sister Gygaea in marriage to the Persian general. According to Justin, Alexander succeeded his father in the kingdom soon after these events. (Hdt. 5.17_21, 8.136 ; Justin, 7.2_4.) In B. C. 492, Macedonia was obliged to submit to the Persian general Mardonius (Hdt. 6.44); and in Xerxes' invasion of Greece (B. C. 480), Alexander accompanied the Persian army. He gained the confidence of Mardonius, and was sent by him to Athens after the battle of Salamis, to propose peace to the Athenians, which he strongly recommended, under the conviction that it was impossible to contend with the Persians. He was unsuccessful in his mission ; but though he continued in the Persian army, he was always secretly inclined to the cause of the Greeks, and informed them the night before the battle of Plataeae of the intention of Mardonius to fight on the following day. (8.136, 140-143, 9.44, 45.) He was alive in B. C. 463, when Cimon recovered Thasos. (Plut. Cim. 14.) He was succeeded by Perdiccas II.

Alexander was the first member of the royal family of Macedonia, who presented himself as a competitor at the Olympic games, and was admitted to them after proving his Greek descent. (Hdt. 5.22; Justin, 7.2.) In his reign Macedonia received a considerable accession of territory. (Thuc. 2.99.)