This includes fantasy and sci-fi.
My choice is the Combine.
A multi-universal species from half-life so absolutely immense and powerful that they reverse-engineered earth's technology, upgraded far beyond human ability, brainwashed some humans and had them invade themselves. They did this and stomped all resistance within 7 hours. This was done by a backwater lesser combine city mind you.
-
Alpacacorns. A race of Alpaca, Unicorn, hybrids. They could fly and shoot rainbows out of their buttocks. They also have the "coolness" of Alpacas. They are the supreme race.