Öljeytü Khan (Chinese: 完澤篤汗; Mongolian: Өлзийт Төмөр, romanized: Ölziit Tömör; ᠥᠯᠵᠡᠶᠢᠲᠦ ᠲᠡᠮᠦᠷ (rotated 90°), Öljeyitü Temür), born Temür (also spelled Timur, Chinese: 鐵穆耳, Mongolian: Төмөр, October 15, 1265 – February 10, 1307), also known by the temple name Chengzong (Emperor Chengzong of Yuan; Chinese: 元成宗; pinyin: Yuán Chéngzōng; Wade–Giles: Yüan2 Ch'eng2-tsung1) was the second emperor of the Yuan dynasty of China, ruling from May 10, 1294 to February 10, 1307. Apart from Emperor of China, he is considered as the sixth Great Khan of the Mongol Empire, although it was only nominal due to the division of the empire. He was an able ruler of the Yuan dynasty, and his reign established the patterns of power for the next few decades. His name means "blessed iron Khan" in the Mongolian language.

Temür was a son of the Crown Prince Zhenjin and a grandson of the Yuan founder Kublai Khan. During his rule, the western khanates of the Mongol Empire accepted the supremacy of the Yuan dynasty.