Yesugei Baghatur or Yesükhei (Modern Mongolian: Есүхэй баатар, Yesukhei baatar; died 1171), was a major chief of the Khamag Mongol confederation and the father of Temüjin, later known as Genghis Khan, was of Borjigin family. Yesugei's name literally means "like nine", meaning he had the auspicious qualities of the number nine, a lucky number to the Mongols.
Yesügei was the son of Bartan Baghatur, who was the second son of Khabul Khan, who was recognized as a khagan by the Jin Dynasty. Khabul Khan was, in turn, the grandson of the Mongol chief Khaidu, the first to try to unite all of the Mongols. Yesugei had two sons by his first wife Sochigel: Behter and Belgutei. The Secret History of the Mongols records that in his youth Temüjin killed his brother Behter in a fight for food. His other half-brother, Belgutei, however was a good friend, and later became a general under Genghis. Yesügei's second and chief wife, Hoelun, a daughter of the Olkhunut forest people, was abducted by Yesügei with help of his elder brother Neguun taij and younger brother Daritai otchigin, from her newlywed husband Chiledu.
Yesügei and Hoelun had four sons Temüjin, (later known as Genghis Khan), Hasar, Hachiun, Temüge and a daughter, Temülen.
After the Hamag Mongol confederation khan Hutula died, the confederation had no elected king, but de facto Yesügei ruled the confederation. Yesügei had a bloodbrother, or anda, Toghrul Khan (later known as Wang Khan). After Yesügei's death, Toghrul initially helped Temüjin in arranging his marriage to Börte and uniting the tribes, but later defected to Genghis' anda and rival, Jamukha.