Most commonly known as an evil twin, the Doppelgänger is described as being a double or look alike of another person. In some traditions, to see the Doppelgänger of a relative or friend portends illness or danger, while seeing the Doppelgänger of oneself is a sure omen of death.
Folklores of the Doppelgänger often tell about how the Doppelgänger gives advice to its “good” counterpart, but sometimes it tends to be misleading or malicious. In some instances, they are also able to plant images or thoughts into the minds of their counterpart, as well as those of their relatives or friends.
Origin: Though the exact origin is unknown, most knowledge of the Doppelgänger comes from the Germans. That includes the name itself, as well as its various meanings. Another well known origin is the Norse vardøger, a spiritual reflection of another.
Appearance: Since the Doppelgänger is a look alike or double of a person, then the appearance of it is that of the person it is a double of. Due to the fact that some believe that the Doppelgänger is a spiritual double, then the Doppelgänger may or may not be spectral. Also, most Doppelgängers are often identified as having no shadow, as well as no reflection in a mirror or upon water.
Influence on the Modern Day: There are not many influences on the modern day by the Doppelgänger, but there are a few. One example of this is episode number 154, “Treehouse of Horror VII” of the Simpsons. In this episode, Bart realizes that when he was born, he was a twin. It was discovered that the other twin was too evil to live in society, thus causing him to be forced to live a life of isolation. It is explained that the other twin was a Doppelgänger, an “evil twin”.