Isao Natsuyagi (夏八木 勲, Natsuyagi Isao, 25 December 1939 – 11 May 2013) was a Japanese film actor. He appeared in more than 100 films from 1963 to 2013.

In 1960, Natsuyagi began attending the Bungakuza actors school while attending Keio University.^[1] He eventually left Keio before graduating and entered the Haiyuza actors school.^[1] After graduating in 1966, he joined the Toei studio and made his film debut with Hone made shaburu.^[1] His first starring role was in Hideo Gosha's Kiba Ōkaminosuke (1966).