Banu Bakr bin Wa'il or Banu Bakr, son of Wa'il (Arabic: بنو بكر بن وائل banū bakr bin wā'il) were an Arabian tribe belonging to the large Rabi'ah branch of Adnanite tribes, which also included Abdul Qays, Anazzah, Taghlib, Banu Shayban and Bani Hanifa. The tribe is reputed to have engaged in a 40-year war before Islam with its cousins from Taghlib, known as the War of Basous. The pre-Islamic poet, Tarafah was a member of Bakr.
Bakr's original lands were in Nejd, in central Arabia, but most of the tribe's bedouin sections migrated northwards immediately before Islam, and settled in the area of Al-Jazirah, on the upper Euphrates. The region of Diyar Bakr, and later the city of Diyarbakır in southern Turkey, take their names from this tribe.
The tribe is distinct from the tribe of Bani Bakr ibn Abd Manat, who lived in the Hejaz and had important interactions with Muhammad.
During the Islamic Prophet Muhammad's era the Banu Bakr tribe was involved in various military conflicts.
The following are some of the related and sub-tribes of Bakr ibn Wa'il in the pre-Islamic and early-Islamic eras: