Kukulkan and some of his animal collection
Kukulkan's starship
Kukulkan (Listen file info) was an ancient and very long-lived being, and the last of his species.
He visited Earth in the distant past, and was instrumental in the technological and architectural advances of the Egyptian, Mayan, and Aztec civilizations. He also taught them new techniques in art and agriculture. He hoped that they would combine this knowledge to complete Kukulkan's city and live in peace; however, they did not. Kukulkan's visit to Earth is manifested in history by legends of a winged serpent creature that came from the sky bringing knowledge. These records were available in the library computer of the Constitution-class USS Enterprise.
He has also been identified with the lore of Quetzalcoatl, as well as the legend of the Chinese dragon. (TAS: "How Sharper Than a Serpent's Tooth")