The mythical hero who traveled to find immortality is Gilgamesh from ancient Mesopotamian mythology. His epic tale recounts his journey to discover the secret of eternal life after the death of his friend Enkidu. Gilgamesh encounters various beings and faces numerous challenges, ultimately realizing that immortality may not be attainable for mortals. His story explores themes of friendship, human vulnerability, and the acceptance of mortality, emphasizing the importance of legacy and the impact one leaves behind.