Nanda Bayin (Burmese: နန္ဒဘုရင်, ; 1535–1600), was the king of the Toungoo Dynasty of Myanmar from 1581 to 1599. Nanda was the eldest son of King Bayinnaung, and became the heir apparent upon his father's accession in January 1551. He was one of lead commanders in all of his father's campaigns that conquered Lan Na, Siam and Lan Xang, among others.
Soon after Nanda succeeded his father in November 1581, he faced the impossible task of keeping his father's empire together. He spent the first half of his reign putting down the rebellions, and the second half defending his own capital against the rebel forces. Siam revolted in 1584 and fought off Nanda's repeated invasions by 1593. By 1597, all the vassal states had revolted. In 19 December 1599, Nanda surrendered to the joint forces of city of Toungoo (Taungoo) and Arakan, and was taken prisoner to Toungoo. He was assassinated a year later by Natshinnaung, the heir apparent of Toungoo.