Stage name

Marilyn Monroe (born Norma Jeane Mortenson) created her stage name by combining her mother's maiden name with the first name of Broadway star Marilyn Miller.

A stage name or professional name is a pseudonym used by performers, authors, and entertainers—such as actors, comedians, singers, and musicians. The equivalent concept among writers is called a nom de plume (pen name). Some performers eventually choose to adopt their stage name as a legal name.

Such professional aliases are adopted for a wide variety of reasons and may be similar or nearly identical to an individual's birth name or be inspired by nicknames or maiden names. Some people take a stage name because their birth name is difficult to pronounce or spell; is considered unattractive, dull, or unintentionally amusing; or projects an undesired image.

From Wikipedia