William Alexander Mouat (9 April 1821 – 11 April 1871) was a British seafarer. Born in London, he spent much of his career with the Hudson's Bay Company in British Columbia on the west coast of Canada. He became master of several merchant ships including the Otter and the Labouchere. His last posting was at Fort Rupert where he died in a canoe accident. He was married to Mary Ann Ainsley and they had eight children.