Samantha Jane Power (born September 21, 1970) is an Irish-American journalist, diplomat, and government official. She was the United States Ambassador to the United Nations from 2013 to 2017, and the Administrator of the United States Agency for International Development from 2021 to 2025. Power is a member of the Democratic Party.

Power began her career as a war correspondent covering the Yugoslav Wars before entering academic administration. In 1998, she became the Founding Executive Director of the Carr Center for Human Rights Policy at Harvard Kennedy School, where she later served as the first Anna Lindh Professor of Practice of Global Leadership and Public Policy until 2009. She was a senior adviser to Senator Barack Obama until March 2008.

Power joined the Obama State Department transition team in late November 2008. She served as Special Assistant to the President and Senior Director for Multilateral Affairs and Human Rights on the National Security Council from January 2009 to February 2013. In April 2012, Obama chose her to chair a newly formed Atrocities Prevention Board. As United Nations ambassador, Power's office focused on such issues as United Nations reform, women's rights and LGBT rights, religious freedom and religious minorities, refugees, human trafficking, human rights, and democracy, including in the Middle East and North Africa, Sudan, and Myanmar. A longtime advocate of armed intervention by the United States in opposition to atrocities abroad, she is considered to have been a key figure in the Obama administration in persuading the president to intervene militarily in Libya.

Power is a subject of the 2014 documentary Watchers of the Sky, which explains the contribution of several notable people, including Power, to the cause of genocide prevention. She won a Pulitzer Prize in 2003 for her book A Problem from Hell: America and the Age of Genocide, a study of the U.S. foreign policy response to genocide. She was awarded the 2015 Barnard Medal of Distinction and the 2016 Henry A. Kissinger Prize. Power's research has been criticized by some in the genocide studies field due to her underlying assumption that the United States was a bystander, as opposed to perpetrator or enabler, of genocide. In 2016, she was listed as the 41st-most powerful woman in the world by Forbes.

Power was born in London, the daughter of Irish parents Vera Delaney, a nephrologist and field-hockey international player, and Jim Power, a dentist and piano player. Raised in Ireland until she was nine, Power lived in the Dublin district of Castleknock and was schooled in Mount Anville Montessori Junior School, Goatstown, Dublin, until her mother separated from her father due to his drinking and immigrated to Pittsburgh, Pennsylvania, in 1979. She has recalled reading Enid Blyton and Nancy Drew mystery novels while accompanying her father to a local pub in Dublin. She recalled: "It was not, clearly, an ideal environment for a child. On the other hand, my father was always just a few steps away, and we were very close, and he was very loving and very present, notwithstanding where it was he was being present."

She attended Lakeside High School in Atlanta, Georgia, where she was a member of the cross country team and the basketball team. She subsequently received her B.A. degree in history from Yale University, where she was a member of Aurelian Honor Society and a reporter for the Yale Daily News, and her J.D. degree from Harvard Law School.

After graduating from Yale, Power worked at the Carnegie Endowment for International Peace as a researcher for Carnegie's then-President Morton Abramowitz. From 1993 to 1996, she worked as a war correspondent, covering the Yugoslav Wars for U.S. News & World Report, The Boston Globe, The Economist, and The New Republic. When she returned to the United States, she attended Harvard Law School, receiving her J.D. in 1999. The following year, her first edited work, Realizing Human Rights: Moving from Inspiration to Impact (edited with Graham Allison) was published. Her first book, A Problem from Hell: America and the Age of Genocide, grew out of a paper she wrote while attending law school; it helped create the doctrine of responsibility to protect. The book won the Pulitzer Prize for General Nonfiction and the J. Anthony Lukas Book Prize in 2003. Power's book framed genocide as a problem that the United States was involved in as an onlooker rather than a perpetrator or enabler. She has been a longtime advocate of the use of armed force by the United States in response to genocide abroad.

In 2004, Power was named by Time magazine as one of the 100 most influential people in the world that year. In fall 2007, she began writing a regular column for Time.