William E. Smith (June 18, 1824 – February 13, 1883) was an American merchant and politician who served as the 14th Governor of Wisconsin, the 5th State Treasurer of Wisconsin, and the 21st Speaker of the Wisconsin State Assembly. He also served four years in the Wisconsin State Senate, representing Dodge County. In business, he was the co-founder of Smith, Roundy & Co., which became the supermarket chain Roundy's.