A pen name, also known as a pseudonym, is a name an author uses in the place of their real name, when they write and publish things. For example, the Brontë sisters (Anne, Emily and Charlotte) who were famous authors in the 19th century used them, because they feared that people would make fun of (say bad things about) a book written by a woman. Charles Dodgson, an English math professor took the name Lewis Carroll, when he wrote fantasy stories. Erle Stanley Gardner, a best-selling American author, wrote books under numerous pseudonyms, including A. A. Fair, Kyle Corning, Charles M. Green, Carleton Kendrake, Charles J. Kenny, Les Tillray and Robert Parr, as well as under his real name.

Famous examples of pen names
 Cecil Adams (author of The Straight Dope column–real name unknown)
 Guillaume Apollinaire (Guillaume Albert Vladimir Apollinaire de Kostrowitzky), 20th century French poet, writer, and art critic
 Tudor Arghezi (Ion N. Theodorescu), 20th century Romanian poet and children's author
 Richard Bachman (Stephen King) 20th century horror author
 W. N. P. Barbellion (Bruce Frederick Cummings), 20th century diarist
 'BB' (Denys Watkins-Pitchford), 20th century illustrator and children's book author
 Beachcomber (D.B. Wyndham-Lewis and John Bingham Morton), used for the surrealist humorous column "By the Way" in the Daily Express
 Acton Bell, Currer Bell, and Ellis Bell (Anne Brontë, Charlotte Brontë, Emily Brontë)
 Nicolas Bourbaki (a group of mainly French 20th-century mathematicians)
 Kir Bulychev (Кир Булычёв) Igor Vsevolodovich Mozheyko (И́горь Все́володович Може́йко), 20th century Russian science fiction writer and historian
 Anthony Burgess (John ['Jack'] Burgess Wilson), 20th century British writer
 Cassandra (William Connor), 20th century left-wing journalist for The Daily Mirror
 Sue Denim (Dav Pilkey), writer and illustrator of the popular "Captain Underpants" children's book series (Sue Denim is a parody of the word pseudonym); also used by science fiction writer Lewis Shiner
 Carter Dickson (John Dickson Carr), 20th century author of detective stories
 Isak Dinesen (Karen Blixen), 20th century Danish author of "Out of Africa"
 H.D. (Hilda Doolittle), 20th century American imagist poet, novelist and memoirist
 George Eliot (Mary Ann Evans), 19th century English novelist
 Paul Eluard (Eugène Grindel) 20th century French Dada and Surrealist poet
 C. S. Forester (Cecil Smith), 20th century writer of the Captain Horatio Hornblower novels, "The African Queen". and other novels
 Anatole France (Jacques Anatole François Thibault), 20th century French author
 Pat Frank (Harry Hart Frank), 20th century author of the apocalyptic novel Alas, Babylon
 Nicci French (Nicci Gerard and Sean French)
 Uriah Fuller (Martin Gardner) wrote Confessions of a Psychic.
 Anthony Gilbert (Lucy Beatrice Malleson), British author of the Arthur Crook crime fiction novels
 George Groth was the name under which Martin Gardner he wrote a negative review of his book, The Whys of a Philosophical Scrivener.
 K. Hardesh (Clement Greenberg), 20th century American art critic
 O. Henry (William Sidney Porter), American author of short stories and novels
 Hergé (Georges Remi), 20th century Belgian comics writer and artist, famous worldwide for creating the Tintin series of books
 Iceberg Slim Robert Beck, an African American writer.
 Jinyong or Kam-yung (Louis Cha), 20th century Chinese-language novelist
 Robert Jordan (James Oliver Rigney, Jr.), the author of the bestselling The Wheel of Time fantasy series.
 Ann Landers (Esther Pauline Friedman), advice columnist
Stan Lee (Stanley Martin Lieber), comic book pioneer
 Maddox (George Ouzounian), The Best Page in the Universe
 Mao Dun (Shen Dehong), 20th century Chinese novelist, cultural critic, and journalist
 Multatuli (Eduard Douwes Dekker), Dutch writer famous for his satirical novel, Max Havelaar (1860)
 Murray Leinster (William Fitzgerald Jenkins), 20th century science fiction author
 Molière (Jean Baptiste Poquelin), 17th century French theatre writer, director and actor, and writer of comic satire.
 Natsume Sōseki (Natsume Kinnosuke), early 20th century Japanese novelist
 Gérard de Nerval (Gérard Labrunie), 19th century French poet, essayist and translator
 Pablo Neruda (Ricardo Eliecer Neftalí Reyes Basoalto) 20th century Chilean poet. Nobel laureate.
 Abu Nuwas (Hasin ibn Hani al Hakami) 8th century Arabic language poet (Persia)
 George Orwell (Eric Arthur Blair), 20th century British author and essayist
 Ouida (Marie Louise de la Ramée), 19th century English novelist
 William Penn (Jeremiah Evarts), 19th century activist against Indian removal
 Q (Arthur Quiller-Couch), late 19th and early 20th century British author, poet, and literary critic
 Ellery Queen (Frederic Dannay and Manfred B. Lee), 20th century detective fiction
 Pauline Réage (Anne Desclos), 20th century French author and critic who wrote Histoire d'O
 Henry Handel Richardson (Ethel Florence Lindesay Richardson), early 20th century Australian author
 Saki (Hector Hugh Munro), early 20th century British satirist
 George Sand (Armandine Lucie Aurore Dupin), 19th century French novelist and early feminist
 Sayeh (ه‍. ا. سایه) Hushang Ebtehaj, 20th century Iranian poet (هوشنگ  ابتهاج)
 Dr. Seuss (Theodore Seuss Geisel), also used "Theo. LeSieg", 20th century American writer and cartoonist best known for his of children's books
 Shahriar (شهریار) Seyyed Mohammad Hossein Behjat-Tabrizi (), an Iranian poet, writing in Persian and Azerbaijani
 Cordwainer Smith (Paul M. A. Linebarger), 20th century science fiction author
 Lemony Snicket (author of A Series of Unfortunate Events–Daniel Handler)
 Stendhal (Marie-Henri Beyle),19th century French writer
 Max Stirner (Johann Kaspar Schmidt), 19th century German philosopher
 James Tiptree, Jr (Alice Sheldon), 20th century science fiction author
 Toegye (Yi Hwang), 16th century Korean Confucian scholar
 Tom Tomorrow (Dan Perkins) 20th century editorial cartoonist
 Lazlo Toth (Don Novello), using name taken from that of a deranged man who vandalized Michelangelo's Pieta in Rome, the pen name was used for the satiric "The Lazlo Letters" and other books
 Trevanian (Dr. Rodney Whitaker), 20th century American spy novelist
 Mark Twain (Samuel Langhorn Clemens, also used "Sieur Louis de Conte" for his fictional biography of Joan of Arc), 19th century American humorist, writer and lecturer
 Abigail Van Buren (Dear Abby - Pauline Esther Friedman Phillips), advice columnist
 Voltaire (François-Marie Arouet), 18th century French Enlightenment writer, deist and philosopher
 Wang Shiwei 王實味 (Wang Sidao 王思禱), 20th century Chinese journalist and literary writer
 Artemus Ward (Charles Farrar Browne), 19th century American humor writer
 Ibn Warraq is a pen name that has traditionally been adopted by dissident authors throughout the history of Islam, including a current writer from India.
 Wonkette (Ana Marie Cox), political gossip weblog writer
 Hajime Yatate (Various Sunrise animation staff members)
 Yulgok (Yi I), 16th century Korean Confucian scholar

Sources