Shiro Saigo (????, Saigo Shiro, February 4, 1866 – December, 1922) was one of the earliest disciples of Judo.
Saigo, together with Tsunejiro Tomita, became first in history of judo to be awarded Shodan by the founder of judo Jigoro Kano, who established the kyu-dan ranking system.
He was one of the Kodokan Shitenno or Four Guardians of the Kodokan along with Yoshitsugu Yamashita, Sakujiro Yokoyama, and Tsunejiro Tomita.