Kephileth

Kephileth (kiːfɪleθ), The Deep Terror, The Provider from the Abyss, an ancient immortal sea beast that was created by Ayathogoth to rule over the oceans of many worlds in the Universe as a protector.

Mythology
"'Swimming in the oceans is the terrible thing ever witnessed by mortal eyes... The enormous power of the Kephileth shall never be challenged for his long and shelled body can destroy a galley of ships and his beak can pierce a thousand shields...Eyes of gold stare at those who sinned and feed on the wickedness of men...Remember the mere mention of this beast shall bring about the end of vast armies...The giants before him perished in the path of the Kephileth never seen again...'"

This gave new evidence of the expansion of Eshermekite culture into other regions of the Fertile Crescent.

Some scholars thought this was their version of Leviathan that was mentioned in the Bible by the Israelites and it was speculated this predated any mention of other legendary beasts.

Yagathian Origins
"'The Kephileth roared and trembled like thunder as he scours the waves of the Forbidden Ocean...This calls for the awakening of the first dawn and harvest of Y'g-the...When the Radiant Race sounds the trumpets and gathers the abundant crops the Kephileth rejoices...Those who refuse to do good in the eyes of him shall perish in the water...'"

This beast was considered to have come from Y'g-'theh as a protector of the Yagathians and also worshipped as he devoured evil within many of the oceans.

The Kephileth might have been the inspiration behind the legend of sea monsters and also mythological creatures from other worlds in the Universe.