Karen Blixen and Julian Barnes both used pseudonyms in their works.
Karen Blixen Baroness Karen Christenze von Blixen-Finecke (née Dinesen; 17 April 1885 – 7 September 1962) was a Danish author who wrote works in Danish and English. She is best known under her pen names Isak Dinesen, used in English-speaking countries, and Tania Blixen, used in German-speaking countries. She also published works using the aliases Osceola and Pierre Andrézel.
Julian May Julian Clare May (born July 10, 1931) is an American science fiction, fantasy, horror, science and children's writer who also uses several literary pseudonyms, best known for her "Saga of Pliocene Exile" ("Saga of the Exiles" in the United Kingdom) and "Galactic Milieu Series" books.