Fujiwara no Teika or Sadaie (藤原定家: 1162–September 26, 1241) was a Japanese waka poet, critic, carigrapher, scribe and scholar of the late Heian and early Kamakura periods.

Teika is known a member of editors' team of Shin-kokin wakashu ordered by the Emperor Go-toba . He also selected the works for the Ogura Hyakunin Isshu, an anthology of a hundred poems by a hundred poets. His Hyakunin Isshu was later thought a book of waka theory in which all types of ideal waka and all technics were consumed.

Teika made many manuscripts of Japanese classics. In his days the ancient Japanese pronunciation was lost and it made the orthography of kana confused. Teika researched old document and assumed the earlier system of differenciation between kana and made an systematic orthography. It had been used till the modern. He applied his kana system to his manuscripts. His manuscripts were known with accuracy and good quality and called Teika bon (Teika text). Using his method he succeeded to document the accurate pronunciation of earlier waka like Kokin waka shu