Before the Second World War, he worked in a Hamburg print shop as chief draftsman for circus and artist posters. Later, he devoted himself increasingly to animal painting and finally became one of the best-known German animal painters and illustrators from the 1950s onwards. He illustrated fairy tale books, animal and nature books, school books and zoo guides. For more than three decades, he was the in-house illustrator of the Hagenbeck Zoo in Hamburg. Among his best-known works was "The Encyclopedia of Animals”. More than five thousand animals are depicted in them. He also worked on "Grzimek's Animal Life". He was also one of the main illustrators for the Kronen-Verlag Erich Cramer and produced a large part of the drawings for the "Sammlung naturkundlicher Tafeln" - mammals and for the series "Cramer's Naturkundliche Anschauungstafeln".
Commissions reached him from all over the world. Behind his artistic success are more than 50 years of diligent drawing and observing, combined with a sound self-study of zoology.
Wilhelm Eigener roamed Africa from Sudan to the Cape with sketchpad and easel. The "Who is Who" counts him among the European celebrities. Erich Cramer also travelled with him to Africa, where they not only painted and sketched, but also shot a film together about the fona and flora in Africa.
In 1977 he was awarded the “Bundesverdienstkreuz am Bande” order of the Federal Republic of Germany.