It seems impossible, but there are a handful of athletes who have achieved medals in both Olympics classes.
Edward Eagan , the only athlete to have achieved gold medals at both the Winter and Summer Olympics. In Antwerp (1920) he won one in boxing, while in Lake Placid (1932) he did the same in four-way bobsleigh.
Jacob Tullin Thams won the gold medal in ski jumping in Chamonix (1924), and the silver medal in sailing in Berlin (1936).
Christa Luding-Rothenburger won gold in speed skating at the Sarajevo Winter Olympics in 1984, and a silver in cycling at the Seoul Summer Olympics in 1988.
Clara Hughes was bronze in cycling time trial at the 1996 Olympic Games in Atlanta, and gold in 5,000 meters of ice skating in Salt Lake City (2002).
