Ono no Komachi (小野 小町?, c. 825 – c. 900) was a Japanese waka poet, one of the Rokkasen — the six best waka poets of the early Heian period. She was renowned for her unusual beauty, and Komachi is today a synonym for feminine beauty in Japan. She also counts among the Thirty-six Poetry Immortals.
Almost nothing of Komachi's life is known for certain, save for the names of various men with whom she engaged in romantic affairs and whose poetry exchanges with her are preserved in the Kokin Wakashū. She was probably born between 820 and 830, and she was most active in composing poetry around the middle of the ninth century.
Extensive study has gone into trying to ascertain her place of birth, her family and so on, but without conclusive results. The Edo-period scholar Arai Hakuseki advanced the theory that there was more than one woman named Komachi and that the legends about her referred to different people. This theory was later expanded to conjecture that there were four "Komachis". It has been conjectured that she was a lady-of-the-bedchamber (更衣 kōi?) in the service of Emperor Ninmyō, and when the latter died in 850 she started relationships with other men.
According to one tradition, she was born in what is now Akita Prefecture, daughter of Yoshisada, Lord of Dewa. The Noh play Sotoba Komachi by Kan'ami describes her as "the daughter of Ono no Yoshizane, the governor of Dewa". Her social status is also uncertain. She may have been a low-ranking consort or a lady-in-waiting of an emperor.