Nanda Bayin, king of Burma (d. 1600)
Nanda Bayin (Burmese: နန္ဒဘုရင်, pronounced [nàɰ̃da̰ bəjɪ̀ɰ̃]; Thai: นันทบุเรง, RTGS: Nantha Bureng; 9 November 1535 – 30 November [O.S. 20 November] 1600), was king of Toungoo Dynasty of Burma (Myanmar) from 1581 to 1599. He presided over the collapse of Toungoo Empire, the largest empire in the history of Southeast Asia.

The eldest son of King Bayinnaung was one of the principal commanders in his father's military campaigns that expanded and defended the empire. As king, Nanda faced the impossible task of keeping his father's "improbable domain" together. He never gained the full support of his father's chosen vassal rulers, who governed what used to be sovereign kingdoms just a few decades earlier. Within the first three years of his reign, both Upper Burma and Siam revolted. Though he could never raise more than a third of his father's troop levels, Nanda could not come to terms with a smaller empire. Between 1584 and 1593, he launched five disastrous invasions of Siam, which increasingly weakened his hold everywhere else. From 1593 onward, it was he who was on the defensive, unable to stop a Siamese invasion that seized the entire Tenasserim coast in 1594–95, or prevent the rest of the vassals from breaking away in 1597. In 1599, Nanda surrendered to the joint forces of Toungoo and Arakan, and was taken prisoner to Toungoo. A year later, he was assassinated by Natshinnaung.Nanda was an energetic king, who probably would have made an "above average" Burmese monarch. But he made the mistake of trying to hold on to an "absurdly overextended" empire built mainly on patron-client relationships. The king's monumental failures taught his 17th century successors not to overextend their realm and to implement a more centralized administrative system. The Restored Toungoo administrative reforms, which with Konbaung modifications, would last to the end of Burmese monarchy in 1885, had their origins in the failures of Nanda Bayin.