Constantine VII Porphyrogenitus (Medieval Greek: Κωνσταντῖνος Πορφυρογέννητος, romanized: Kōnstantīnos Porphyrogénnētos; 17 May 905 – 9 November 959) was the fourth Byzantine emperor of the Macedonian dynasty, reigning from 6 June 913 to 9 November 959. He was the son of Emperor Leo VI and his fourth wife, Zoe Karbonopsina, and the nephew of his predecessor Alexander.
The epithet porphyrogenitus alludes to the Purple chamber of the imperial palace, decorated with porphyry, where legitimate children of reigning emperors were normally born. Constantine was also born in this room, although his mother Zoe had not been married to Leo at that time. Nevertheless, the epithet allowed him to underline his position as the legitimate son, as opposed to all others, who claimed the throne during his lifetime. Sons born to a reigning Emperor held precedence in the Eastern Roman line of succession over elder sons not born "in the purple".
Constantine VII is still remembered in the Eastern Orthodox liturgy when the transfer of the Holy Mandylion is celebrated on 16 August in the Julian calendar which corresponds to 31 August in the Gregorian calendar. This feast is part of the Nut Feast of the Saviour for Slavs.