Semimaru

right|thumb|200px|Semimaru, from the Hyakunin Isshu.

was a Japanese poet and musician of the early Heian period. His name is recorded in the Ogura Hyakunin Isshu, but there are no historical accounts of his pedigree. Some accounts say he was a son of Uda Tennō, Prince Atsumi, or that he was the fourth son of Daigo Tennō. There are also claims that he lived during the reign of Ninmyō Tennō.