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 856 he engineered Theoktistos's fall and became the 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.

Bardas (Βάρδας) Mamikonian war von 856 bis 866 Regent für den byzantinischen Kaiser Michael III.. Er war der Sohn von Marinos Mamikonian und der Bruder der Kaiserin Theodora, der Ehefrau des Kaisers Theophilos. Seine Familie entstammt der armenischen Dynastie der Mamikonian.

Bardas est régent (856 - 866) de l'empereur byzantin Michel III.

Bardas fu reggente dell'impero bizantino, dal 856 al 866.