William Anthony Kirsopp Lake, best known as Tony Lake, (born April 2, 1939) is the Executive Director of the United Nations Children's Fund (UNICEF), author, academic, and former American diplomat, Foreign Service Officer, and political advisor. He has been a foreign policy advisor to many Democratic U.S. presidents and presidential candidates, and served as National Security Advisor under U.S. President Bill Clinton from 1993 to 1997. Lake is credited as being one of the individuals who developed the policy that led to the resolution of the Bosnian War. He also held the chair of Distinguished Professor in the Practice of Diplomacy at the Edmund A. Walsh School of Foreign Service at Georgetown University, in Washington, D.C.

Lake is the grandson of Kirsopp Lake, a member of the Church of England clergy who came from Oxford, England, to America in order to teach New Testament studies at Harvard. Lake's father, Gerard Kirsopp Lake, was a New Deal Democrat and his mother Eleanor (née Eleanor van Someren Hard), a Republican.

Lake himself was born in New York City. He attended Middlesex School and Harvard College, graduating with a Bachelor of Arts degree in 1961. Lake studied international economics at Trinity College, Cambridge and later received a Ph.D from the Woodrow Wilson School of Public and International Affairs at Princeton University in 1974.