An alter ego is defined as the "other self," but it also can mean a second self or the manifestation of another personality within the same person, as in a personality disorder. It may also mean a close friend who is a constant companion.
Psychoanalysis
Freudian theory postulates that an alter ego is a personality disorder in which a person can exhibit multiple, distinct personalities. These separate personalities are known as alter egos or alters.
Law
Alter ego is a business term defining an individual or a group of individuals that has conducted business illegally and unethically while representing a business.
Relationships
An alter ego also describes a very close friend and someone who is always around.
Literature
An alter ego is also a device used in literary works. In the novella, "The Strange Case of Dr. Jekyll and Mr. Hyde," by Robert Louis Stevenson, Mr. Hyde is the alter ego of Dr. Jekyll.
Popular Culture
Many performers use an alter ego for their performances, such as Beyonce, who uses the alter ego Sasha Fierce.
