Bayinnaung Kyawhtin Nawrahta (Burmese: ဘုရင့်နောင် ကျော်ထင်နော်ရထာ [bəjɪ̰ɰ̃ nàʊɰ̃ tɕɔ̀ tʰɪ̀ɰ̃ nɔ̀jətʰà]; Thai: บุเรงนองกะยอดินนรธา, RTGS: Burengnong Kayodin Noratha listen ; 16 January 1516 – 10 October 1581) was king of the Toungoo Dynasty of Myanmar from 1550 to 1581. During his 31-year reign, which has been called the "greatest explosion of human energy ever seen in Burma", Bayinnaung assembled what was probably the largest empire in the history of Southeast Asia, which included much of modern-day Myanmar, the Chinese Shan states, Lan Na, Lan Xang, Manipur and Siam.Although he is best remembered for his empire building, Bayinnaung's greatest legacy was his integration of the Shan states into the Irrawaddy Valley-based kingdoms. After the conquest of the Shan states in 1557–1563, the king put in an administrative system that reduced the power of hereditary Shan saophas, and brought Shan customs in line with lowland norms. It eliminated the threat of Shan raids into Upper Burma, an overhanging concern since the late 13th century. His Shan policy was followed by Burmese kings right up to the final fall of the kingdom to the British in 1885.Bayinnaung could not replicate this administrative policy everywhere in his far-flung empire, however. His empire was a loose collection of formerly sovereign kingdoms, whose kings were loyal to him as the Cakkavatti ("Universal Ruler"), rather than to the Kingdom of Toungoo itself. Indeed, Ava and Siam revolted just over two years after his death. By 1599, all the vassal states had revolted, and the Toungoo Empire completely collapsed.

Bayinnaung is considered one of the three greatest kings of Burma, along with Anawrahta and Alaungpaya. Some of the most prominent places in modern Myanmar are named after him. He is also well known in Thailand as the Phra Chao Chana Sip Thit (พระเจ้าชนะสิบทิศ, "Conqueror of the Ten Directions").