King Taksin the Great (Thai: สมเด็จพระเจ้าตากสินมหาราช, RTGS: Somdet Phra Chao Taksin Maharat, listen ) Emperor of Siam (Thai: จักรพรรดิแห่งสยาม) or the King of Thonburi (Thai: สมเด็จพระเจ้ากรุงธนบุรี, RTGS: Somdet Phra Chao Krung Thon Buri; simplified Chinese: 郑昭; traditional Chinese: 鄭昭; pinyin: Zhèng Zhāo; Teochew: Dên Chao; Vietnamese: Trịnh Quốc Anh 鄭國英; April 17, 1734 – April 7, 1782) was the only King of the Thonburi Kingdom. He had been an aristocrat in the Ayutthaya Kingdom and then was a major leader during the liberation of Siam from Burmese occupation after the Second Fall of Ayutthaya in 1767, and the subsequent unification of Siam after it fell under various warlords. He established the city of Thonburi as the new capital, as the city of Ayutthaya had been almost completely destroyed by the invaders. His reign was characterized by numerous wars; he fought to repel new Burmese invasions and to subjugate the northern Thai kingdom of Lanna, the Laotian principalities, and a threatening Cambodia.

Although warfare occupied most of Taksin's reign, he paid a great deal of attention to politics, administration, economy, and the welfare of the country. He promoted trade and fostered relations with foreign countries including China, Britain, and the Netherlands. He had roads built and canals dug. Apart from restoring and renovating temples, the king attempted to revive literature, and various branches of the arts such as drama, painting, architecture and handicrafts. He also issued regulations for the collection and arrangement of various texts to promote education and religious studies.

He was taken in a coup d'état and executed, and succeeded by his long-time friend Maha Ksatriyaseuk, who then assumed the throne, founding the Rattanakosin Kingdom and the Chakri dynasty, which has since ruled Thailand. In recognition for what he did for the Thais, he was later awarded the title of Maharaj (The Great).