What is the most famous photographic portrait ever taken? Some would say it is this one of Sharbat Gula, an Afghan woman who became famous as a cover photograph on a 1985 issue of National Geographic magazine.
While at the Nasir Bagh refugee camp in Pakistan in 1984, her picture was taken by National Geographic photographer Steve McCurry. Gula was one of the students in an informal school within the refugee camp; McCurry, rarely given the opportunity to photograph Afghan women, seized the opportunity and captured her image. Read more about this photo in the Wikipedia article.