Tumen Zasagt Khaan (Tümen Jasagtu Khan) was a 16th-century Mongol Khagan of the Northern Yuan Dynasty in Mongolia who reigned from 1558 to 1592. He was the successor of Darayisung Gödeng Khan and had direct rule over the Chahar. It was during his rule that the Mongols conquered Daur and Evenks. Unlike his father, he succeeded in uniting the entire Mongol people, including the Western Mongols, with little bloodshed. Zasaghtu Khan died in 1592.