Zoë Porphyrogenita (Medieval Greek: Ζωή Πορφυρογέννητη Medieval Greek: [zoˈi] "life"; c. 978 – 1050) was a member of the Macedonian dynasty who briefly reigned as Byzantine Empress in 1042, alongside her sister Theodora. Before that she was enthroned as empress consort to a series of co-rulers, two of whom were married to her.

Zoë was born when her father Constantine was nominal co-emperor to his brother, Basil II. After a marriage to Holy Roman Emperor Otto III in 996 failed to materialise, Zoë spent subsequent years in the imperial palace. Basil died in 1025 when Zoë was 47, and her father acceeded the Byzantine throne as Constantine VIII. As he had no sons, Constantine hoped to continue the dynasty by marrying off one of his daughters. Zoë, aged 50, was married to Romanos Argyros. They took the throne the next day on her father's death.

The marriage of Zoë and Romanos III was troubled, and Romanos was found dead in his bath in 1034. His death has been variously attributed to Zoë, her young lover, or both. They were married on the same day as the supposed murder, and he was crowned Emperor Michael IV on the following day. In 1041, Zoë was persuaded to adopt her dying husband's nephew, Michael Kalaphates. Once Michael V became emperor, he promptly exiled Zoë. This action sparked a popular revolt which dethroned him and installed Zoë and her sister Theodora as joint empresses. After a two-month joint reign, Zoë married a former lover who was installed as Constantine IX, transferring power to him. However, she continued to rule the empire as its heir and as the Byzantine empress. Eight years later, Zoë died aged 72. Her reign saw the decline of the Roman army, and the first incursions by the Turks into eastern Anatolia.