Alexander (Greek: Αλέξανδρος, Alexandros), (c. 870–913) was the third son of Emperor Basil I and Eudokia Ingerina. Unlike his older brother Leo VI the Wise, his paternity was not disputed between Basil I and Michael III because he was born years after the death of Michael.

Alexander was named crowned co-emperor by his father in 879. Upon his brother's death on May 11, 912 Alexander succeeded as senior emperor alongside Leo's young son Constantine VII. Alexander promptly dismissed most of Leo's advisers and appointees, including the admiral Himerios, the patriarch Euthymios, and the Empress Zoe Karbonopsina. The patriarchate was again conferred on Nicholas Mystikos. During his short reign, Alexander found himself attacked by the forces of Al-Muqtadir of the Abbasid Caliphate in the East, and provoked a war with Simeon I of Bulgaria by refusing to send the traditional tribute on his accession. Alexander died of exhaustion after a polo game on June 6, 913, allegedly fulfilling his brother's prophesy that he would reign for 13 months.

The sources are uniformly hostile towards Alexander, who is depicted as lazy, lecherous, and malignant, including the rumor that he planned to castrate young Constantine VII in order to exclude him from the succession. At least that charge did not come to pass, but Alexander left his successor a hostile regent (Nicholas Mystikos) and the beginning of a long war against Bulgaria.

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