gustaf archibald siegwart douglas (born 3 march 1938) is the oldest son of count carl ludvig douglas (26 july 1908 stjärnorp - 21 january 1961 rio de janeiro), a swedish nobleman and diplomat who was royal swedish ambassador to brazil, and his prussian wife ottora maria haas-heye (13 february 1910 partenkirchen - 17 july 2001).