Temülün (c. 1171–?) was the youngest full sibling and only sister of Genghis Khan (born Temüjin), the famed founder and Great Khan of the Mongol Empire. Her parents were Yesügei, chief of the Borjigin clan in the Khamag Mongol confederation, and his second wife Hö'elün. She was nine years younger than Temüjin.
Born into the Olkhonud clan of the Onggirat tribe, Hö'elün was originally married to Chiledu, a Merkit aristocrat; she was captured shortly after her wedding by Yesügei, an important member of the Mongols, who abducted her to be his primary wife. She and Yesügei had four sons and one daughter: Temüjin, Qasar, Hachiun, Temüge, and Temülen. After Yesügei was fatally poisoned and the Mongols abandoned her family, Hö'elün shepherded all her children through poverty to adulthood—her resilience and organisational skills have been remarked upon by historians. She continued to play an important role after Temüjin's marriage to Börte—together, the two women managed his camp and provided him with advice.