She was a famous actress, a humanitarian, a mother, an advocate for children, goodwill ambassador to UNICEF, and an extremely stylish, classy and beautiful woman. She was born in 1923 and died in 1993. In terms of her acting career, I always think of "Breakfast at Tiffanys" (1961) first when I think of Audrey Hepburn, although I don't know if that is generally considered her seminal work. Other famous movies she did include "My Fair Lady" and "Roman Holiday".
Here is a picture of her when she was 59 and still beautiful:
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You can read more about her here and at many other web sites:
http://www.audreyhepburn.com/
cfitz