William Anthony Kirsopp Lake is an American diplomat and political advisor who served as the 17th United States National Security Advisor from 1993 to 1997 and as the sixth Executive Director of UNICEF from 2010 to 2017.

The Assistant to the President for National Security Affairs (APNSA), commonly referred to as the National Security Advisor (NSA), is a senior aide in the Executive Office of the President, based at the West Wing of the White House. The national security advisor serves as the principal advisor to the President of the United States on all national security issues.