Bardas (; died 21 April 866) was a
Byzantine noble and high-ranking minister. As the brother of Empress
Theodora, he rose to high office under
Theophilos (r. 829–842). Although sidelined after Theophilos's death by Theodora and
Theoktistos, in 855 he engineered Theoktistos's murder and became the
de facto regent for his nephew,
Michael III (r. 842–867). Rising to the rank of
Caesar, he was the effective ruler of the Byzantine Empire for ten years, a period which saw military success, renewed diplomatic and
missionary activity, and an intellectual revival that heralded the
Macedonian Renaissance. He was assassinated in 866 at the instigation of Michael III's new favourite,
Basil the Macedonian, who a year later would usurp the throne for himself and install
his own dynasty on the Byzantine throne.