Queen Mandukhai (/ˌmændʊˈxaɪ/; Mongolian: Мандухай хатан, IPA: [mantʊ̆χɛ́ː χátʰə̆ɴ]), also fully known as Wise Queen Mandukhai (Мандухай сэцэн хатан; c. 1449 – 1510), was a queen of the Northern Yuan. With her second husband Batmunkh Dayan Khan, she helped reunite the warring Mongols.

Mandukhai was the only daughter of Chororsbai-Tumur, chingsang (grand councillor) of the Ongud Mongols in eastern Mongolia. Her family were aristocrats. In 1464 at the age of sixteen, Mandukhai was married to Manduul Khan, who ruled the Northern Yuan from 1473 to 1479. Mandukhai began to take precedence over Yungen Qabar-tu, the khan's childless first wife. Most sources report that Manduul Khan had no children, although two names are sometimes mentioned as daughters of Mandukhai. Based on their ages, it is possible they were in fact relatives of Manduul Khan, rather than daughters, and may have been cared for by Mandukhai.

In approximately 1478 or 1479, Manduul Khan died under uncertain circumstances. He had no clear heir, leaving several Mongol princes struggling to succeed him as the Khan. His senior wife, Yeke Qabar-tu, disappeared, her fate unknown.

Mandukhai brought from hiding and adopted the seven-year-old orphan Batumunkh, son of the late Bayan Mongkhe Jonon, a direct descendant of Genghis Khan and part of the Altan Urug, who had also been killed by Esmel (Ismail). As Batumunkh was the last living descendant of Genghis Khan, Mandukhai had him proclaimed Dayan Khan, and she rejected the marriage offer by Unubold, a powerful noble. However, Unubold, himself a descendant of Hasar, a younger brother of Genghis Khan, remained loyal to Mandukhai and the child Khan.

With command over the Mongols, Mandukhai made war with the Oirats and defeated them. Her stunning victory over the Oirats brought back great reputation of the Borjigins and united Mongolia for the first time in more than one hundred years. According to the Yellow Chronicle of the Oirat, a history of the Oirats, Mandukhai imposed the following symbolic laws upon the Oirats in order to mark her dominance over them:

The Yellow Chronicle also reports that the Oirats were prohibited to eat meat with knives after Mandukhai's conquest. Anthropologist Jack Weatherford considered such a prohibition unlikely to have been an actual law. He suggested that after the conquest, Mandukhai may have temporarily confiscated the weapons of the Oirats, including their knives. They would have had to tear at their meat with their teeth until they were permitted to carry weapons and knives again.

When Batumunkh turned nineteen, she married him and retained her control over the Mongols. The Oirats again rebelled and raided the Eastern Mongols. Mandukhai led the great army against them. She defeated several Ming dynasty attacks and protected the Northern Yuan, she wore the helmet and the sword and fought with the Ming soldiers. She was pregnant, but still fought and delivered twin boys during a long battle. The Western Mongols were subdued once again.

From 1480, Dayan Khan and Mandukhai increased the pressure on the Ming territory because they closed the border trade and killed a Northern Yuan envoy. To contain her, the Ming rapidly expanded the Great Wall. She reoccupied Ordos area and stationed soldiers there to keep watch on the Ming. She reenthroned Dayan Khan at the Eight White Yurts in Ordos but they had to flee a Ming attack. Mandukhai with Dayan Khan went to the Kherlen River in 1501 though her husband continued raids on the Ming dynasty.