Baydu (Mongolian script:; Байду) (died 1295) was the sixth ruler of the Mongol empire's Ilkhanate division in Iran. He was the son of Taraqai, who was in turn the fifth son of Hulagu Khan. He succeeded his cousin Gaykhatu as khan of the Ilkhanate state in 1295.
He was born in Mongolia to Taraqai and Qaraqcin. His father was Hulagu's fifth son but he was killed by lightning strike on his way to Iran. Baydu and his mother arrived at Iran with Qutui Khatun's camp alongside Tekuder and other princes in 1269. Reportedly, he never commanded an army and was considered to be easy to be controlled by Mongol emirs. He participated in Abaqa Khan's invasion of Syria in 1281. During his predecessors reigns, he was a viceroy in Jazira.
He was considered as one of candidates to Ilkhanid throne after death of Arghun. Nobles like Taghachar, Qoncuqbal, Toghan and Tuqal supported Baydu, however he refused throne stating throne belongs to the brother or a son according to yassa, while Mahmud Aqsarai simply states that when Baydu didn't appear at the quriltai, Gaykhatu was enthroned instead. Baydu stood stationed in Baghdad and even travelled to coronation feast of new khan Gaykhatu. However, after getting drunk Gaykhatu insulted Baydu telling one of his servants to hit Baydu. This grew a resentment in Baydu towards him. Baydu left hastily towards to his appanage near Baghdad leaving his son Qipchak as a hostage in Gaykhatu's court. He was supported by Oirat emir Chichak (son of Sulaimish b. Tengiz Güregen), Lagzi Küregen (son of Arghun Aqa), El-Temur (son of Hinduqur Noyan) and Todachu Yarquchi, who followed him to Baghdad. He was also aided by his vizier Jamal ud-Din Dastgerdani. According to Hamdullah Qazwini, Baydu's main motivation on moving against Gaykhatu was his sexual advances against Qipchak.
When son-in-law Ghurbatai Güregen brought him news of treachery, Gaykhatu ordered arrest of several amirs including his personal keshig Tuladai, Qoncuqbal, Tukal, Bughdai, including Kipchak and put into jail in Tabriz.