1. Doppelgänger- definition:
Doppelgänger comes from the German word which means “double-walker”. The English dictionaries define it s a paranormal double of a living person.
It has now come to be associated with a non-paranormal look alike.
The double, both in literature and out of it, is an enormous and seductive subject. As an imagined figure, a soul, a shadow, a ghost or a mirror reflection that exists in a dependent relation to the original, the double pursues the subject as his second self and makes him feel as himself and the other at the same time. While its imaginative power springs from its immateriality, from the fact that it is and has always been a ghost, the psychological power of the double lies in its ambiguity, in the fact that it can stand for contrast or opposition, but likeness as well.

2. The androgyny= the double?
A well known version of the androgyny myth is narrated by Plato, in the Symposium, through the character named Aristophanes, explaining the way in which the love appeared and trying to give us a magnificent image of the androgyny.
It can be complementarity, as in the Platonic conception of twin souls which seek each other in order to make a whole out of their sundered halves. Sympathy between individuals, even human love, can also be seen as one aspect of the dialectic between 'I" and "non-I", the subject and his double, upon which the possibility of wholeness and integration within the self rests.
Since the early beginning of literature the double motif serves in its different models to trace the features of the ego, individuality and perception. The double plays an important role in literature: it pictures confusion and transformation, reflects inner desires and spreads anxiety. But the phenomenon is not just an invention of literature. Again and again people claim to see oneself.

3. Different types of Doppelgängers
First level: appearance of visually identical twins
This type of Doppelgänger is knows as your “evil-twin”. This evil twin is unknown to the original person but causes mischief to their families and friends.
The Double motif is not an invention of the 19th century. It can already be found in the works of antique authors as well as in mythology. 
From these predecessors a first of three levels of development of the Double motif which can be recognized can be deduced.
 This first level is expressed by the appearance of visually identical twins that are components of such a comedy of mistaken identities and form the centre of confusion. This comedy develops traces of tragedy because the characters are forced to the edge of insanity because of the emotional mix-up. But in the end the pair(s) of twins face each other which helps to dissolve these confusions and there is an happy ending.

4. Second level: 1 person 2 characters
It could categorize in someone having a look-a-like or having a second individual who share the same interests as you
In the second level of development[4] there is a dramatic change in the Double motif: Out of one single person arise two characters. One person splits into two characters, which look alike like in the first level, during the plot. But the Double is just a part of the original and they are both complementary to each other.

5. Third level: the persons mostly do not look alike
The two characters are one person but they never appear at the same time in the same scenery. The second self can be recognized as weird and disconcerting as it fulfils depressed desires of the ego.
The persons of the third level mostly do not look alike but it still belongs to the Double motif within research literature. In this temporarily last level of development the two characters are one person but they never appear at the same time in the same scenery. The second self can be recognized as weird and disconcerting as it fulfils depressed desires of the ego. It embodies the shady side, the part of life which the ego avoided to realize.
It can be said that in all of these three levels of development there is an endangerment of the identity of a person. The alter ego is the opponent of the ego with its existence and personal living conditions. Especially in the third level the double changes the values of the main character and turns his live upside down.

6. Sigmund Freud- The Uncanny
Freud was fascinated by the mysteries of creativity and the imagination. The groundbreaking works that comprise The Uncanny present some of his most influential explorations of the mind.
In 1919 Sigmund Freud wrote his essay The Uncanny in which he is in search of the anthropological roots of the Double motif.
In 1919 Sigmund Freud wrote his essay The Uncanny in which he is in search of the anthropological roots of the Double motif. Already in 1911 he wrote a letter to his friend C.C. Jung in which he writes about his interpretations of the appearance of pairs of twins in some mythologies. So, in Freud’s opinion the ancestors of the Doppelganger motif can be traced back till the mythical thinking in antiquity. This is one origin of the faith in the immortality of the soul and some of these beliefs can still be found in some European superstitions. So, people thought that the Double embodies the immortal imaginary soul of the human individual.

7. Carl Gustav Jung- Concept of Archetypes
"The archetype concept derives from the often repeated observation that myths and universal literature stories contain well defined themes which appear every time and everywhere. We often meet these themes in the fantasies, dreams, delirious ideas and illusions of persons living nowadays“ –Carl Gustav Jung
Unlike Freud, Jung sees the Self as completely opposite, where good and evil are simply complementary opposites, each a necessary condition for the existence of the other. In his doctrine of the shadow he defines the double as as neither good nor bad, but as "a replica of one's own unknown face." It acquires a demonic aspect only because one side of the personality is repressed and subordinated to an absolute good. Seeing the double as a force of neither good nor evil, Jung recovers something of its original mythical meaning and directs attention to the particular historical and social constraints against which it protests and from which it is generated. Jung defines the double as a manifestation of desire, which seeks that which is experienced as absence and loss and points to its main function. Never ceasing to express the desire for unity with the lost centre of personality, never losing its transcendental quality, the double in modern literature expresses itself as a violent transgression of human limitations and of social taboos which prohibit the realization of desire. The "other" has been categorized as a negative black area – as evil, demonic, barbaric – until it is recognized as the unseen of culture.

8. Edgar Allan Poe
Born January 19, 1809 in Boston, MA; died October 1, 1849 in a bar in a foreign country. Famous American poet know for his dark and mysterious works of murder and madmen. 1st well-known American to try to earn a living through writing alone
One of the creators of the Gothic style, the inventor of the detective genre, adding romantic influences in the same time, Edgar Allan Poe is best known through his stories in which mistery is mixed with the macabre.
The theme adopted by Poe, both in prose and poetry, it is not indeed a cultural association with written literature in America at the time. His characters suffer, unconditionally, a loss of judgement, falling easily, in the area of mental disorder and nerve, the pathological and sangvinic impulses. The heroes are dying and resurrecting, misleading, killing and becoming, with brutality, accomplices to crime, they have the “grotesque” satisfaction and reveal psychological and intellectual complexities.

9. William Wilson
“I have lost. Yet from now on you are also dead — dead to the World, dead to Heaven, dead to Hope! In me you lived — and, in my death — see by this face, which is your own, how wholly, how completely, you have killed — yourself!”
The short story, „William Wilson”, follows the theme of doppelganger. The novel treats the subject of the double, another self that haunts the narrator character, leading him to insanity, becoming even his own insanity. William, the protagonist, meets another boy in school who had the same name and looked surprisingly like him. He dressed and even walked like him. The only difference between them was that the doppelganger of William could only talk in a whisper. The doppelganger haunts William all his life. Worn out by interference from his double in his affairs, William stabs him only to find in the mirror that he has stabbed himself. He hears the voice of his rival as if it was his own.
Poe’s vision of the world that emerges from his novel is the idea that the man is the maker of his own destiny. He is the only one capable of, as through an accumulation of will, changing something in his own way of life. He is not alone, being guided by his independent forces, but he must want to see them and listen. Otherwise, the man is not only a killer of his own soul, but unworthy to bear forth wisdom the universe.

10. Bibliography: Snodrass Mary Ellen, Encyclopedia of Ghotic Literature