Mark Ellis (born 4 February 1945) is an American-Canadian naval architect, who has designed sixteen production sailboats, along with many custom sailboats and powerboats. He is best known for his Nonsuch series of catboats, the Limestone series of powerboats and Niagara sailboats. In 2003, Dan Spurr described Ellis as "one of Canada's premier yacht designers". Ellis was born in Watertown, New York, United States. He currently lives in Oakville, Ontario, Canada and holds dual American citizenship and Canadian citizenship.