The Bagratuni or Bagratid dynasty was an Armenian royal dynasty which ruled the medieval Kingdom of Armenia from c. 885 until 1045. Originating as vassals of the Kingdom of Armenia of antiquity, they rose to become the most prominent Armenian noble family during the period of Arab rule in Armenia, eventually establishing their own independent kingdom.

Ashot I, nephew of Bagrat II, was the first member of the dynasty to rule as King of Armenia. He was recognized as prince of princes by the court at Baghdad in 861, which provoked war with local Arab emirs. Ashot won the war, and was recognized as King of the Armenians by Baghdad in 885. Recognition from Constantinople followed in 886. In an effort to unify the Armenian nation under one flag, the Bagratids subjugated other Armenian noble families through conquests and fragile marriage alliances. Eventually, some noble families such as the Artsrunis and the Siunis broke off from the central Bagratid authority, founding the separate kingdoms of Vaspurakan and Syunik, respectively. Ashot III the Merciful transferred their capital to the city of Ani, now famous for its ruins. They kept power by playing off the competition between the Byzantine Empire and the Arabs.

With the start of the 10th century and on, the Bagratunis broke up into different branches, fragmenting the kingdom in a time when unity was needed in the face of Seljuk and Byzantine pressure. The rule of the Ani branch ended in 1045 with the conquest of Ani by the Byzantines.

The Kars branch of the family held out until 1064. The junior Kiurikian branch of the Bagratunis continued to rule as independent kings of Tashir-Dzoraget until 1118 and Kakheti-Hereti until 1104, and thereafter as rulers of smaller principalities centered on their fortresses of Tavush and Matsnaberd until the 13th century Mongol conquest of Armenia. The dynasty of Cilician Armenia is believed to be a branch of the Bagratids, which later took the throne of an Armenian Kingdom in Cilicia. The founder, Ruben I, had an unknown relationship to the exiled king Gagik II. He was either a younger family member or kinsman. Ashot, son of Hovhannes (son of Gagik II), was later governor of Ani under the Shaddadid dynasty.