Sadao Nakajima (Japanese: 中島貞夫, Hepburn: Nakajima Sadao, August 8, 1934 – June 11, 2023) was a Japanese film director and screenwriter known for his work in yakuza films and jidaigeki.

Born in Tōgane, Chiba, he attended Hibiya High School and then the University of Tokyo before joining the Toei studio in 1959.

[1] Working at Toei's Kyoto studio, he served as an assistant director under such directors as Masahiro Makino, Tadashi Imai, and Tomotaka Tasaka.

[2] He made his directorial debut in 1964 with Kunoichi Ninpō, and won the Directors Guild of Japan New Directors Award in 1966 for Yakuza (893) Gurentai, the first gendaigeki shot at Toei's Kyoto studio.

[3][4] He directed such popular film series as Kogarashi Monjirō and Nihon no Don, and also worked in television.