A mermaid is a legendary aquatic creature with the upper body of a female human and the tail of a fish. Mermaids appear in the folklore of many cultures worldwide, including the Near East, Europe, Africa and Asia.The first stories appeared in ancient Assyria, in which the goddess Atargatis transformed herself into a mermaid out of shame for accidentally killing her human lover.hereafter, she took the form of a mermaid — human above the waist, fish below — although the earliest representations of Atargatis showed her as a fish with a human head and arm, similar to the Babylonian god Ea.