Al-Adil Sayf ad-Din Tuman Bay () was the twenty fifth Mamluk Sultan of Egypt from the Burji dynasty. He ruled for about one hundred days in 1501.
Tuman Bay I was about forty years old when he was selected as Sultan. Although he was popular before becoming a Sultan, he soon lost that popularity due to his cruel measures, which was manifested in condemning one of the princes to death by hanging for alleged conspiracy.
He was overthrown and succeeded by Al-Ashraf Qansuh al-Ghawri.
He was married to the Mamluk noblewoman FÃÂá¹Âima bint ÿAlë ibn Khaṣṣbak (d. 1505), the rich widow of sultan Qaitbay (r. 1468-1497) and sister of Zaynab bint ÿAlë ibn Khaṣṣbakd, who was the widow of Sultan Sayf al-Din Inal (r. 1453-1461).