Doppelganger

Doppelgangers were monstrous humanoids, infamous for their shapeshifting abilities that allowed them to mimic almost any humanoid creature. They were lazy but cunning creatures, who killed or disposed of people then assumed their place. While not actually evil, doppelgangers were extremely self-centered and liable to look down on their victims. They were believed to be an artificial race, created by the Creator Race known as the batrachi. They had a fondness for working with the magically inclined; mainly being used as assassins or in elaborate plots to usurp power.

Doppelgangers were feared for their ability to assume the form of any humanoid creature they encounter. Doppelgangers were used as spies and assassins by many beings all over the world.

Many doppelgangers lived a stolen life. When they encountered a person whose appearance or station they desired for themselves, the doppelganger used their mental powers to learn everything they could about the chosen target. Once they had all the knowledge they needed, they quietly eliminated their target and assumed his or her form, taking their place in life.

Physical characteristics
In their true form, doppelgangers appeared as tall, elven, gray-skinned humanoids, whose thin bodies made them appear, to human eyes, sexless. Even this form was deceptive, suggesting they were physically weak, when in fact they were quite strong and agile. The normal appearance of a doppelganger was that of a gray-skinned humanoid with a formless face and pale white eyes. They had no hair in their normal form.

Culture
Doppelganger families tended not to be close; usually a male and female meet, engaged in casual sex, then left one another, with the female being forced to single-handedly rear any resulting newborns—who left their mother upon reaching maturity. Some however, formed tightly knit family clusters, while others mated with humanoids, taking malicious delight in using their spouse as a cover for their inhumanity. Children born of such unions had a chance of being a half-doppelganger.