Gustaf Axel Estlander (18 September 1876 – 1 December 1930) was a Finnish architect and one of the most successful Scandinavian yacht designers of the early 20th century. He was born and educated in Finland, later set up a yacht yard in Germany, and spent his final years in Sweden. As a sporty youth, Estlander in 1894 sailed from Finland to Sweden in a canoe. He was an accomplished skater, winning the 1898 European Speed Skating Championships for Men in Helsinki, Finland. He also competed at the 1912 Summer Olympics.