Theodora (Θεοδώρα) Porphyrogenita, or Porphyrogenniti (Πορφυρογέννητη) was a Byzantine and Eastern Roman empress of the 11th century. She was the daughter of Constantine VIII and the sister of Zoe Porphyrogenniti. She spent much of her time co-ruling with Zoe. She was known for her excessive control over her personal enemies and sought to centralize as much power as possible which made her unpopular. Michael VI Bringas was elected to be her successor as she refused to choose an heir.