Walter Alexander Riddell (5 August 1881 – 27 July 1963) was a Canadian civil servant, diplomat, and academic. He was the Canadian Advisory Officer to the League of Nations from 1924 to 1937. Born in Stratford, Ontario to a single working parent, Riddell was the deputy minister of the Department of Labour for the Government of Ontario. From 1920 to 1925, he was the Canadian delegate to the International Labour Organization in Geneva. From 1924 to 1937, he was the Canadian Advisory Officer to the League of Nations. From 1940 to 1946, he was the Canadian High Commissioner to New Zealand. He later taught International Relations at the University of Toronto.