Aten are a species of Mystical Creatures in the Course Books.
The Atens' territories are at least as extensive, or larger than the human-colonized Known Worlds. They stay largely within their own territory, and seldom allow anyone into it; wherefore, the full extent is unknown. They have been known, in the distant past, to have interbred with other species, and so produced the Druid race and other Passers.
Aten are Mystical Creatures and can therefore assume a variety of shapes; but on human worlds, they are usually portrayed with a generally hominid appearance, with some distinctive feature to set them apart from modern humanity: these may vary, but usually supply large eyes, up-turned eyebrows, long dexterous fingers, lithe limbs, and large pointed ears to both sexes. They are said, as well, to be long-lived (or even immortal): so long-lived, in fact, that the word for 'modern' in their language, refers to any time later than the Mage Wars.
Aten have a long and intricate history, known to very few outside their own territories. Perhaps the best-known of their customs is Hearts' Day, on which they celebrate the bicentennial anniversaries of recent marriages.