Banu Bakr ibn Wa'il or Banu Bakr, son of Wa'il are an Arabian tribe belonging to the large Rabi'ah branch of Adnanite tribes, which also includes 'Anizzah, Taghlib, 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 is a member of Bakr.Bakr's original lands are in Nejd, in central Arabia, but most of the tribe's Bedouin sections migrate northwards immediately before Islam, and settle in the area of Al-Jazirah, on the upper Euphrates.

The region of Diyar Bakr, and later the city of Diyarbakir in southern Turkey, take their names from this tribe.Most of the bedouins of Bakr in al-Yamama join the rest of the tribe in Mesopotamia after the appearance of Islam, where they have good relations with the tribe of 'Anizzah.

However, some inhabitants of al-Yamama continue to trace their descent from Bakr through Bani Hanifa up to the modern era, particularly in Riyadh.