Theodora (Greek: Θεοδώρα; c. 815 – c. 867), sometimes called Theodora the Armenian or Theodora the Blessed, was Byzantine empress as the wife of Byzantine emperor Theophilos from 830 to 842 and regent for the couple's young son Michael III, after the death of Theophilos, from 842 to 856. Theodora is most famous for bringing an end to the second Byzantine Iconoclasm (814–843), an act for which she is recognized as a saint in the Eastern Orthodox Church. Though her rule saw the loss of most of Sicily and failure to retake Crete, Theodora's foreign policy was otherwise highly successful; by 856, the Byzantine Empire had gained the upper hand over both the Bulgarian Empire and the Abbasid Caliphate, and the Slavic tribes in the Peloponnese had been forced to pay tribute, all without decreasing the imperial gold reserve.
Possibly of Armenian descent, Theodora was born into a rural family of traders and military officials in Paphlagonia. In 830 she was selected by Euphrosyne, step-mother of the emperor Theophilos, as a candidate in a bride-show for the young emperor. After being chosen by Theophilos she was crowned empress on 5 June 830. Theophilos was an iconoclast, who opposed the veneration of icons; it is unclear how aware he was that Theodora was an iconophile. The couple had seven children and Theodora was a loyal participant in imperial affairs and ceremonies, but she continued to secretly venerate icons throughout her husband's reign. Theophilos died of dysentery on 20 January 842, probably younger than 30. On his deathbed, he named Theodora as regent for their two-year-old son Michael III and designated a selection of advisors to assist her. The most prominent of these advisors was the logothete and eunuch Theoktistos, who would become a close confidant of Theodora.