Denmark has issued stamps since 1851. The first person to be featured on a Danish stamp was King Christian IX. The years appearing after each name refer to when that person was first featured on a stamp.
... Parry[?], (born 1790), Arctic explorer
Robert Edwin Peary, (1856-1920), first man to reach the North Pole
Auguste Piccard, (1884-1962), physicist and explorer
Jacques ...