President Sirleaf became Liberia's first elected female president in 2006.  Fellow Liberian Leymah Gbowee is an activist recognized for uniting women against the country's warlords. Tawakkol Karman is a Yemeni journalist and the first Arab woman to receive the prize.

When they received the award on December 10 in Oslo, Norway, they joined a special group - an elite group of women winners.

This year, the Norwegian Nobel Committee split the US$1.5 million prize among three women.

A total of 15 women have received the Nobel Peace Prize since it was first awarded in 1901. The first was Austrian writer and peace activist Bertha von Suttner in 1905.

The most recent woman to receive the prize was Kenyan environmentalist Wangari Maathai in 2004.  Maathai died in September after a long battle with cancer.

Women have also won Nobel Prizes in the sciences and literature, with one woman, radiation researcher Marie Curie, honored twice, first in physics and years later in chemistry.