Theophylact or Theophylactus (Latin: Theophylactus; Greek: Θεοφύλακτος Theophylaktos, "guarded by God") may refer to:

• Theophylact Simocatta (7th century), Byzantine author and historian
• Theophylactus (Exarch) (died 710), Exarch of Ravenna
• Patriarch Theophylactus of Alexandria (7th–8th centuries), coadjutor Greek Orthodox Patriarch of Alexandria
• Theophylact of Antioch (8th century), Greek Orthodox Patriarch of Antioch
• Archdeacon Theophylact (8th century), archdeacon of the Roman Church
• Peter of Atroa or Theophylact (773–837)
• Theophylact Rhangabe (8th century), Byzantine admiral
• Theophylact (son of Michael I) (793–849), Byzantine co-emperor
• Theophylact of Nicomedia (died 845), Bishop of Nicomedia
• Theophylact I, Count of Tusculum (9th–10th centuries)
• Theophylact of Constantinople (917–956), Patriarch of Constantinople
• Theophylact Dalassenos (10th–11th centuries)
• Theophylact Botaneiates (fl. died 1014)
• Pope Benedict VIII or Theophylactus (died 1024)
• Pope Benedict IX or Theophylactus (11th century)
• Theophylact of Ohrid (died c. 1107), Archbishop of Ohrid and biblical commentator
• Theophylaktos (died 1958), Metropolitan of Australia; see List of 20th-century religious leaders