It's said that eyes are the window to the soul, and in fiction, their color is often the first way to hint at a character's true nature. In particular, characters who have gold and yellow-colored eyes tend to have some form of supernatural origin or powers that place them above normal humans and very often have an animalistic side to them. In the real world, several creatures have this eye color -- ducks (you read right), wolves, foxes, owls, cheetahs (though their eyes are most commonly copper or light brown), lions, domestic cats, bearded dragons, and quite a few others. Humans can also possess this eye color, though it is rare, or at least very uncommon.