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Even though it might be tempting to suggest that the story of Perseus killing Gorgon could have derived from the Gilgamesh story of the slaying of Humbaba, here it is only suggested that one can find iconographic parallels between the depictions of these stories in Mesopotamia and Greece.
The link could be provided by a Cyprian cylinder seal, which depicts a demon-giant beaten down to one knee and about to be slain by Perseus, who is armed with the Assyrian-Cyprian sickle or harpe. It is a typical depiction of the demon versus the hero in Ancient Near Eastern art (characteristics include the depiction of the head and body in full front, with the legs in profile).
The iconography of this cylinder seal bears striking resemblance to Assyrian depictions on seals of the slaying of Humbaba by Gilgamesh and Enkidu, while also with depictions of Gorgon in Greece later in the 6th century BCE.
Bibliography
Croon 1955
Croon, J. H. The Mask of the Underworld Daemon. Some Remarks on the Perseus-Gorgon Story. Journal of Hellenic Studies 75 (1955) 9-16. [JSTOR (requires subscription)]
Hopkins 1934
Hopkins, Clark. Assyrian Elements in the Perseus-Gorgon Story. American Journal of Archaeology 38 (1934) 341-358. [JSTOR (requires subscription)]
Illustrations (click an image to view the full-size version in a new window)
Fig. 1: A modern impression of a Cyprian cylinder seal depicting the hero versus the demon-giant (Perseus vs Gorgon?). VA 2145 Photo courtesy of the Vorderasiatisches Museum Berlin.
Fig. 2: Gorgon from the west pediment of the Temple of Artemis, Corfu, Greece. Limestone, ca. 580 BC. Archaeological Museum of Corfu, Greece. Courtesy of the Deutsches Archäologisches Institut, Athens.
Fig. 3: A modern impression of a Neo-Assyrian period cylinder seal, belonging to Dr. Leonard Gorelick (http://classics.uc.edu/~johnson/myth/gilgamesh_images/humbaba.jpg ).