Ō no Yasumaro (太 安万侶?, died August 15, 723) was a Japanese nobleman, bureaucrat, and chronicler. He may have been the son of Ō no Honji (多 品治?), a participant in the Jinshin War of 672.
He is most famous for compiling and editing, with the assistance of Hieda no Are, the Kojiki, the oldest extant Japanese history. Empress Genmei (r. 707-721) charged Yasumaro with the duty of writing the Kojiki in 711 using the differing clan chronicles and native myths. It was finished the following year in 712.
Yasumaro most probably also played an active role in compiling the Nihon Shoki, which was finished in 720.
Yasumaro became clan head in 716, and died in 723.
On January 23, 1979 the grave of Ō no Yasumaro was unearthed in a tea plantation in Konose Ward of Nara City. Its engraving reads:
左京四條四坊従四位下勲五等太朝臣安萬侶以癸亥
年七月六日卒之 養老七年十二月十五日乙巳
"Ō no Yasumaro, Junior 4th Grade Lower, 5th Grade Order of Merit, who lived in the 4th Ward of 4th Street in the Right Capital,
Who died in 6th day of the 7th month of 7th year of Yōrō [Inscribed on] the 15th day of 12th month [by] Ki no Tomi"
Yasumaro appears in the video game Toukiden: The Age of Demons as a mitama (a soul of a hero from Japanese history).