Tayy (Arabic: طيء‎) is a large and ancient Arabian tribe belonging to the southern or Qahtanite branch of Arab tribes. Their original homeland was the area of the two mountains Aja and Salma in north central Arabia (currently Ha'il Province, Saudi Arabia), though, like all Qahtanite tribes, it is believed they originally moved there from Yemen. The tribe shared the area with Bani Assad and Bani Tamim, and its members included both nomads and settled town-dwellers.

The tribe is believed to have included a number of Christians before Islam, though most of the tribe's members are reported to have been pagan. The most famous figure from Tayy in that period was the legendary Hatim Al-Ta'i (Hatim of Tayy), said to be a Christian, and renowned among the Arabs for generosity and hospitality. He also figures in the Arabian Nights. The early Islamic historical sources report that his son, 'Adiyy ibn Hatim, whom they sometimes refer to as the "king" of Tayy, converted to Islam before Muhammad's death. He is particularly revered by the Shi'a, who consider him a partisan of Ali. Another figure from Tayy during this period was Zayd al-Khayr, a prominent member of Tayy who is said to have led Tayy's delegation to Muhammad accepting Islam.