Mongol commander in Persia (fl. 1230-1260, also known as Bayju or Baichu) appointed by Ögedei Khan to succeed Chormagan, and expand Mongol power further in that area.

Baiju took over command in 1241 or 1242, and immediately moved against the Sultanate of Rüm, shattering its power at the Battle of Kose Dagh. After this battle, the Sultanate became a vassal state of the Mongol empire. However, the Mongols had few forces in the area, and were content to maintain their vassals with punitive raids.

At the end of the regency following Ögedei's death, however, Baiju was replaced by the new khan Güyük with Eljigidei in Iran, and tolerated the independence of the Sultanate, Georgia, and petty states in Iran as clients, interefering with dynastic succession and extracting tribute militarily as necessary. However, the Abbasids in Baghdad and the Assassins in the Elbruz mountains maintained their independence until the coming of Hulegu, Möngke's brother, in 1255.

Baiju was supposedly reproached by Hulegu for failing to extend Mongol power further, and, indeed, was replaced by him as supreme commander as early as 1255, but served under him ably in further campaigns: against the Sultanate of Rum (to extract tribute and replace the sultan), in the assault on Baghdad in 1257, and in the adavance on Syria towards Egypt in 1259.

It is unclear what happened to Baiju after that: when the Mongol force was heavily depleted by the departure of Hulegu in 1260, the force that remained was commanded by Kitbuqa. It seems likely, then, that Baiju retired from the front line, returning to either Persia proper or back to Mongolia, before the defeat at Ayn Jalut, although it is possible he was killed there.