Constantine VII Porphyrogennetos or Porphyrogenitus, "the Purple-born" (that is, born in the imperial bed chambers) (September 2, 905 – November 9, 959), is the fourth Emperor of the Macedonian dynasty of the Byzantine Empire, reigning from 913 to 959.

He is the son of the emperor Leo VI and his fourth wife, Zoe Karbonopsina, and the nephew of his predecessor, the emperor Alexander.

Most of his reign is dominated by co-regents: from 913 until 919 he is under the regency of his mother, while from 920 until 945 he shares the throne with Romanos Lekapenos, whose daughter Helena he marries, and his sons.

Constantine VII is best known for his four books, De Administrando Imperio, De Ceremoniis, De Thematibus, and Vita Basiliii.

His nickname alludes to the Purple Room 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 allows him to underline his position as the legitimized son, as opposed to all others who claim the throne during his lifetime.

Sons born to a reigning Emperor hold precedence in the Eastern Roman line of succession over elder sons not born "in the purple".