Paulicianism (Classical Armenian: Պաւղիկեաններ, Pawłikeanner; Ancient Greek: Παυλικιανοί, "The followers of Paul"; Arab sources: Baylakānī, al Bayāliqa البيالقة) was a Medieval Christian sect which originated in Armenia in the 7th century. Followers of the sect were called Paulicians and referred to themselves as Good Christians. Little is known about the Paulician faith and various influences have been suggested, including Gnosticism, Marcionism, Manichaeism and Adoptionism, with other scholars arguing that doctrinally the Paulicians were a largely conventional Christian reform movement unrelated to any of these currents.

The founder of the Paulicians is traditionally held to have been an Armenian by the name of Constantine, who hailed from a Syrian community near Samsat in modern-day Turkey. The sect flourished between 650 and 872 around the Byzantine Empire's frontier with the Arab Caliphate in Armenia and Eastern Anatolia, despite intermittent persecutions and deportations by the imperial authorities in Constantinople. After a period of relative toleration, renewed Byzantine persecution in the mid 9th century prompted the Paulicians to establish a state centered on Tephrike in the Armenian borderlands under Arab protection.

After prolonged warfare, the state of Tephrike was destroyed by the Byzantines in the 870s. Over the next century, some Paulicians migrated further into Armenia, while others were relocated by the imperial authorities to the Empire's Balkan frontier in Thrace. In Armenia, the Paulicians were assimilated into the related religious movement of Tondrakism over the next century. In Thrace, the sect continued practicing their faith for some time, in some places until the 17th–18th centuries, before gradually converting to other religions and are considered to be the ancestors of the modern Roman Catholic Banat Bulgarians and the Muslim Pomaks. The movement may have also been an influence on medieval European Christian heteredox movements such as Bogomilism and Catharism.