Sei Shōnagon (清少納言, c. 966–1017 or 1025) was a Japanese author, poet, and a court lady who served the Empress Teishi (Sadako) around the year 1000 during the middle Heian period.

When her court service ended she may have married Fujiwara no Muneyo, governor of Settsu province, and had a daughter, Koma no Myobu, although some evidence suggests she became a Buddhist nun.

"[5] Shōnagon is also known for her rivalry with her contemporary, writer and court lady Murasaki Shikibu, author of The Tale of Genji who served the Empress Shoshi, second consort of the Emperor Ichijō.

Shōnagon became popular through her work The Pillow Book, a collection of lists, gossip, poetry, observations and complaints written during her years in the court, a miscellaneous genre of writing known as zuihitsu.

Shōnagon's essays describe the various daily experiences and customs of the time, and the affairs of the Imperial Court in Kyoto where she lived, from a unique point of view.

First printed in the 17th century, it exists in different versions: the order of entries may have been changed by scribes with comments and passages added, edited, or deleted.

[citation needed] Shōnagon writes with apparent lightheartedness about events at court, de-emphasizing or omitting harsh realities such as Teishi's death from childbirth in 1001.

[7] She was also known to be especially adept at recalling and quoting a classic poem to suit the occasion, even by the standards of a court in which knowledge of the poetry canon was considered an essential skill.

A social requirement was that the male send a poem on beautiful paper with a decorative flower or branch to the lady, and that she reply.

Another tradition has her marrying Fujiwara no Muneyo, the governor of Settsu province, after her court service ended, and having a daughter, Koma no Myobu.