Trần Thánh Tông (October 12, 1240 – July 3, 1290), personal name Trần Hoảng (), was the second emperor of the Trần dynasty, reigning over Đại Việt from 1258 to 1278. After ceding the throne to his son Trần Nhân Tông, Thánh Tông held the title of retired emperor () from 1279 to his death in 1290. During the second and the third Mongol invasions of Đại Việt, Retired Emperor Thánh Tông and Emperor Nhân Tông were credited as the supreme commanders who led the nation to the final victories and, as a result, established a long period of peace and prosperity over the country. With his successful rulings in both military and civil matters, Trần Thánh Tông was considered one of the greatest emperors of not only the Trần dynasty but also the whole dynastic era in the history of Vietnam.