Prince Yên Sinh Trần Liễu (1211–1251) was the elder brother of the Trần Thái Tông, the first emperor of Trần Dynasty. Initially, Trần Liễu was honoured by his younger brother with the title King Hiển (Vietnamese: Hiển Hoàng) but he was downgraded to Prince Yên Sinh after the short-lived revolt in fury of losing his pregnant wife, Princess Thuận Thiên, to the Emperor under the pressure of Imperial Regent Trần Thủ Độ. Besides this event, Trần Liễu was well known in the history of Vietnam for being father of Trần Hưng Đạo, commander-in-chief of the Đại Việt army during the second and third war of resistance against the Mongol invasion.