Trần Thái Tông (birth name: Trần Cảnh, 17 July 1218 – 4 May 1277) was the first emperor of the Trần Dynasty, seated on the throne for 33 years (1226–58), being Grand Emperor for 19 years.

Trần Thái Tông's given name was "Trần Cảnh" (). He was born in 1218 during the last years of the Lý Dynasty. Trần Thủ Độ, his uncle, prepared the way for his marriage to Queen Lý Chiêu Hoàng, the last queen of the Lý Dynasty, who later abdicated to make him the founder of the Trần Dynasty in 1226.

His progress to the throne in particular and the replacement of the Trần Dynasty over the Lý Dynasty in general were mostly thanks to the efforts of Trần Thủ Độ, Trần Cảnh's uncle. At that time, Trần Thủ Độ was the front commander of citadels of the Lý Dynasty. Trần Cảnh's father, Trần Thừa, was also an official under the Lý Dynasty, like Trần Thủ Độ. He had been "Nội thị khán thủ", one of the most important officials in the Lý Dynasty.

During his reign Trần Thái Tông used three era names: Kiến Trung (1225–1232), Thiên Ứng Chính Bình (1232–1250) and Nguyên Phong (1251–1258).

He commanded the armies, and decided not to protect his capital from the first Mongol invasion of Vietnam in 1258. Instead, with the help of his military commanders, he opted for small scale battles and guerrilla warfare. Even though he finally forced the Mongols to retreat, he agreed to send tribute every 3 years to the court of the Mongol Empire.

Learned in both Confucianism and Buddhism, he ruled the country wisely and authored several profound works on Buddhism, the most famous of which is Khoa Hu Luc (Instructions on Emptiness), a Zen manual. A prodigious writer, he left behind a substantial number of works, of which only a small number survive.

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