866 deaths

Frankish noble

Abū al-ʿAbbās Aḥmad ibn Muḥammad al-Mustaʿīn bi-ʾllāh (; 836 – 17 October 866), better known by his regnal title al-Mustaʿīn, was the Abbasid caliph from 862 to 866, during the "Anarchy at Samarra". A grandson of Caliph al-Mu'tasim, he was installed on the throne by the Turkic military commanders following the death of al-Muntasir.

King of Asturias

King of Aquitaine from 855

Chinese Chan Buddhist monk (?–866)

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 (. 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 (). 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 assassinate

Duke of Saxony

Frankish saint

Emir of Morocco from 863 to 866

Frankish noble

Countess of Anjou and Blois (c.820–c.866)

Emenon (or Emeno) was the Count of Poitou (828–839), Périgord (863–866), and Angoulême (863–866).

Beatified German nun

French abbot

Shia muhaddith

Bishop of Utrecht

French priest

noble man

Ibrahim ibn Jaʽfar al-Mutawakkil (; died 866), better known by his laqab '''al-Mu'ayyad''' (), was an Abbasid prince, the third son of the Abbasid caliph al-Mutawakkil, He was the governor of Syria from 850 to 861 and also for a time third-in-line to the Abbasid throne.

chief judge (qadi al-qudat) of the Abbasid Caliphate (died 866)