Constantine VII Porphyrogenitus (Greek: Κωνσταντῖνος Πορφυρογέννητος, translit. Kōnstantinos Porphyrogennētos; 17 May 905 – 9 November 959) was the fourth Emperor of the Macedonian dynasty of the Byzantine Empire, 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 Emperor Alexander.

Most of his reign was dominated by co-regents: from 913 until 919 he was under the regency of his mother, while from 920 until 945 he shared the throne with Romanos Lekapenos, whose daughter Helena he married, and his sons. Constantine VII is best known for the Geoponika (τά γεοπονικά), an important agronomic treatise compiled during his reign, and his four books, De Administrando Imperio (bearing in Greek the heading Πρὸς τὸν ἴδιον υἱὸν Ῥωμανόν), De Ceremoniis (Περὶ τῆς Βασιλείου Τάξεως), De Thematibus (Περὶ θεμάτων Άνατολῆς καὶ Δύσεως), and Vita Basilii (Βίος Βασιλείου).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".