Baron Nagayo Sensai (長与 専斎, October 16, 1838 – September 8, 1902) was a medical doctor, educator and statesman in Meiji period Japan.

After studies at the Gokōkan domain academy he studied rangaku under Ogata Kōan in Osaka, and returned to Ōmura afterwards to accept an official position with the domain and rank of samurai.

With the establishment of the Nagasaki Naval Training Center and Dutch military advisors in Nagasaki in 1860, Nagayo assisted Matsumoto Jun and Dutch physician J. L. C. Pompe van Meerdervoort in establishing a medical training college which combined eastern and western medical practices.

After the Meiji Restoration, in 1871 Nagayo was selected to accompany the Iwakura Mission on its around-the-world journey to the United States and Europe.

After his retirement from medicine in 1891, Nagayo served on the Genrōin and became an appointed member House of Peers in the Diet of Japan.