Seiichiro Kashio, Japanese tennis player (d. 1962)

Seiichiro Kashio (柏尾 誠一郎, Kashio Seiichirō, January 2, 1892 – September 6, 1962) was a tennis player from Japan, and with Ichiya Kumagae was one of the first Japanese Olympic medalists. He won the Canadian Open by defeating United States player Walter K. Wesbrook 3–6, 6–3, 6–1, 11–9.