Sei Shōnagon (lit. "lesser councilor of state Sei", real name unknown), (c. 966–1017 or later)
A Japanese court lady (女房 nyoubo) and diarist who served the Empress Teishi (Sadako) around the year 1000 during the middle Heian period. She was involved in a court rivalry with Murasaki Shikibu, lady-in-waiting to second empress consort Shoushi. Her fate is uncertain, by most accounts either taking up Buddhist vows or marrying a provincial governor.
She was an influential figure in Japanese literature, being best known as the author of The Pillow Book (枕草子 makura no sōshi). The book is both a personal diary and an eclectic collection of lists, musings and poetry, a format that created the genre of zuihitsu (随筆) that is often compared to the contemporary medium of blogging.