Thekla (Greek: Θέκλα; early 820s or 830s – after 870), Latinized as Thecla, was a princess of the Amorian dynasty of the Byzantine Empire. The eldest child of Byzantine emperor Theophilos and empress Theodora, she was proclaimed augusta in the late 830s. After Theophilos's death in 842 and her mother becoming regent for Thekla's younger brother, Michael III, Thekla was associated with the regime as co-empress alongside Theodora and Michael and became the second reigning empress of the Empire after Empress Irene of Athens, ruling alongside her brother.
Thekla was deposed by Michael III, possibly alongside her mother, in 856 and consigned to a convent in Constantinople. Some time later, she allegedly returned to imperial affairs and became the mistress of Michael's friend and co-emperor Basil I. After Basil murdered Michael in 867 and took power as the sole emperor, Thekla was neglected as his mistress and she took another lover, John Neatokometes. Once Basil found out about the affair, Thekla fell out of favor, was beaten, and had her property confiscated.
Life
Thekla was born on an uncertain date, as calculating her date of birth depends on the year her parents married, estimated to be either c. 820/821, or 830. Thus she was born in either the early 820s or the early 830s. The historian Warren Treadgold gives her a birth date of c. 831, and the historian Juan Signes Codoñer of Spring 822. She is presented by contemporary sources as the eldest child of Byzantine emperor Theophilos and empress Theodora; but, some historians, such as John Bagnell Bury and Ernest Walter Brooks, have argued that her sister Maria was the eldest on the basis that she is the only one of the daughters to have been engaged, and generally the eldest married first. She was named after Theophilos's mother, Thekla. Thekla had six siblings: the four sisters Anna, Anastasia, Pulcheria, and Maria, whom Theophilos took great pride in, and the two brothers Constantine and Michael. Constantine, who shortly after birth had been proclaimed co-emperor by their father, drowned in a palace cistern as an infant.
In the 830s, the eldest sisters Thekla, Anna, and Anastasia were all proclaimed augustae, an honorific title sometimes granted to women of the imperial family. This event was commemorated through the issue of an unusual set of coins that depicted Theophilos, Theodora, and Thekla on one side and Anna and Anastasia on the other. Although Theophilos was a staunch iconoclast, and thus opposed the veneration of icons, Thekla was taught to venerate them in secret by her mother and Theophilos's step-mother Euphrosyne. Theophilos built a palace for Thekla and her sisters at ta Karianou. Shortly before his death, Theophilos worked to betroth Thekla to Louis II, the heir to the Carolingian Empire, to unite the two empires against the threat they faced from continued Arab invasions. Such a match would also have been advantageous for Louis II's father Lothair I, who was engaged in a civil war against his brothers. Because of Lothair's defeat at the Battle of Fontenoy in 841 and Theophilos's death in 842, the marriage never happened.