Dr. Nancy McNally serves as National Security Adviser in the administration of President Josiah Jed Barlet. She, along with White House Chief of Staff Leo McGarry and Chairman of the Joint Chiefs of Staff Percy Fitzwallace, is among the president's top advisors on foreign policy and military actions. Somewhat unpredictable in her opinions, though always able to support them, she can be both aggressive and extremely careful when it comes to advising the president on how to deploy the armed forces.