Viscount Yamao Yōzō (山尾 庸三, November 5, 1837 – December 21, 1917) was a Japanese samurai of the late Edo period who became an influential member of the Meiji era government of Japan.

Five of the young Choshu samurais, so called Chōshū Five soon left Japan for London from Nagasaki to study western knowledge in 1863 with help of Thomas Blake Glover.

Two of his colleagues Itō Hirobumi and Inoue Kaoru returned to Japan to try and stop Chōshū domain going to war with the Western powers, but Yamao and two other remained and studied science and industry at University College London.

After Morel died in October 1871, Yamao had to find new advisor for establishment of the engineering college, and eventually contacted Hugh Matheson again through good offices of McVean.

Colin Brown was Euing Lecturer of Music in the Andersonian College, and compiled "Songs of Scotland: New Symphonies and Accompaniments (1873)" together with J. Pittman, "Auld Langsyne" on page 21.