Pseudonyms are used by many celebrities. One version is the "pen name" (nom de plume) which is a variant form of a real name adopted by an author and printed on the title page or by-line of his or her works in place of their "real" name.
Why use a pseudonym? Actors and other often change their names to make them sound more "normal," less ethnic or even to sound more exotic. Authors might do it for those reasons too, but they also have other reasons.
The French phrase nom de plume is occasionally used as a synonym for the English term "pen name." This known as "back-translation." The term nom de plume "evolved" in Britain, but there was already the term nom de guerre used in French. The British didn't understand that particular usage as guerre means "war" in French and for authors this made no sense, so they created (not borrowed) their own "French" phrase.
Lemony Snicket is the pen name of American novelist Daniel Handler, and Lemony is also the narrator of many of his novels. He used the name while doing research for his first book when he needed to give a name in order to obtain materials that were "offensive" because he didn't want to use his real name.
Some authors, mostly women, have used pseudonyms to disguise gender and ensure that their works were accepted by publishers and/or the public.
Mary Ann Evans wrote under the pen name George Eliot.
Amandine Aurore Lucile Dupin, Baronne Dudevant, used the much more common pseudonym George Sand.
Charlotte, Emily and Anne Brontë had published under the names Currer, Ellis, and Acton Bell respectively.
Karen Blixen's book Out of Africa was originally published under the pen name Isak Dinesen.
I used to teach the popular young adult novel The Outsiders which is listed on the cover as being written by S.E. Hinton. And that is the author's name and initials, but S.E. is Susan Eloise Hinton. The male-oriented novel might not have had many male readers if it carried a female name.
Other women using initials include Harry Potter creator J. K. (Joanne) Rowling, K. A. Applegate, P. N. Elrod, D. C. Fontana, G. A. Riplinger and J. D. Robb.
Initials can also be used to avoid confusion with another author or notable individual. The very famous British politician Winston Churchill wrote under the name Winston S. Churchill to distinguish his work from the then better known American novelist of the same name.
Mathematician and fantasy writer Charles Dodgson, also wrote his Alice and Wonderland fiction as Lewis Carroll.
Samuel Langhorne Clemens used the aliases Mark Twain and less often Sieur Louis de Conte for different works.
Joseph Conrad was the Anglicized choice made by Józef Teodor Konrad Korzeniowski, the 20th-century Polish-British author.
American author of short stories and novels, O. Henry, was really William Sydney Porter.
Stephen King published four novels under the name Richard Bachman because publishers didn't feel the public would buy more than one novel per year from a single author.
Anne Rice (Howard Allen Frances O'Brien) also used two other aliases: Anne Rampling and A.N. Roquelaure.
The haiku master Matsuo Bashō had used two other haigō before he became fond of a banana plant (bashō) that had been given to him by a disciple and started using it as his pen name starting at age 36.
At one time in France, a nom de guerre was a "war name" adopted or assigned to new recruits as he enlisted in the French army. These pseudonyms were official and a kind of predecessor of identification numbers.
Soldiers were identified by their first names, their family names, and theirnoms de guerre. These pseudonyms were usually related to the soldier's place of origin. Jean Paul dit Champigny might be used for a soldier coming from a town Champigny. In 1716, a nom de guerre was mandatory for every enlisted soldier. Some of these noms de guerre eventually replaced the real family name.
Revolutionaries and resistance leaders that came later and outside of France, such as Lenin, Trotsky, Golda Meir, Philippe Leclerc de Hauteclocque, and Josip Broz Tito, sometimes adopted their noms de guerre as their proper names.