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. Sometimes a performer adopts a name that is unusual or outlandish to attract attention. Some individuals use a stage name because their birth name is already being used by another notable individual, including names that are not exactly the same but still too similar; many guilds and associations that represent actors mandate that no two members may have identical working names. Other performers use a stage name in order to retain anonymity, as is often the case for porn stars, especially if they intend on switching careers. The phrase nom de porn is sometimes used to refer to a pornographic actor's stage name, referring to the English use of the French-language phrase for pen name.

Some individuals who are related to a celebrity take a different last name, so they are not perceived to have received undue advantage from their family connection. Actor Nicolas Cage, born Nicolas Coppola, chose a new last name to avoid comparisons with his uncle, director Francis Ford Coppola, who gave him his big break in the 1982 film Fast Times at Ridgemont High.

Conversely, individuals who wish to receive benefits from their family connections may take that person's first or last name. Lon Chaney Sr.'s son Creighton spent a number of years appearing in minor roles before renaming himself Lon Chaney Jr. Likewise, Emilio Estevez and his sister Renee chose not to take their father Martin Sheen's professional name and use their birth names. Their brother Carlos chose to use their father's professional name and took the name Charlie Sheen. Some children born outside marriage to a (usually male) celebrity parent have done the same: Jett Williams (née Antha Bell Jett) and Scott Eastwood (né Scott Clinton Reeves) each use their fathers' last names; while others have not: Joseph Baena, son of Arnold Schwarzenegger, chose not to use his father's last name.

Women who achieve fame after marriage often use their married name as part of their professional name, while women who achieved fame before marriage may continue to use their maiden name or a hyphenated surname.

In some cases, the individual may adopt a stage name to avoid confusion with other family members who have similar names. Actor Mark Harmon (Thomas Mark Harmon) uses his middle name professionally to avoid confusion with his father Heisman Trophy winner and former broadcaster Tom Harmon (Thomas Dudley Harmon).

Stephen Nice, the birth name of the lead singer of Steve Harley and Cockney Rebel, took on the stage name Steve Harley after realising that his on stage persona differed greatly from his real-life persona, and as a result feeling that he was no longer "Ronald and Joyce's (Harley's parents) little boy" when on stage.

Comedian Amos Muzyad Yaqoob Kairouz adopted the stage name Danny Thomas, largely because he did not want his friends and family to know he had gone back into working clubs where the salary was better.