The hero associated with the quest for immortality in Sumerian mythology is Gilgamesh. In the epic narrative, he embarks on a journey to discover the secret of eternal life after facing the death of his close friend, Enkidu. His quest ultimately leads him to Utnapishtim, who reveals the futility of seeking immortality, teaching Gilgamesh that humans must embrace their mortality. Gilgamesh's journey reflects profound themes of friendship, loss, and the quest for meaning in life, as he learns to find fulfillment in human experiences rather than eternal existence.