A pen name, also called a nom de plume or a literary double, is a pseudonym (or, in some cases, a variant form of a real name) adopted by an author and printed on the title page or by-line of their works in place of their real name.

A pen name may be used to make the author's name more distinctive, to disguise the author's gender, to distance the author from their other works, to protect the author from retribution for their writings, to merge multiple persons into a single identifiable author, or for any of a number of reasons related to the marketing or aesthetic presentation of the work.

The author's real identity may be known only to the publisher or may become common knowledge.