Kate Harper is the Deputy National Security Advisor, played by Mary McCormack, in The West Wing. She joins the series as a recurring character in season five and becomes part of the main ensemble in seasons six and seven.
Harper is portrayed as a highly experienced national-security official. Before working in the Bartlet White House, she served in the Navy and the CIA, giving her a background that differs from the administration’s more overtly political staffers. She works under National Security Advisor Nancy McNally and takes on many of McNally’s responsibilities.
The role is easy to mix up because several women hold senior national-security or policy positions in the series. Nancy McNally is the National Security Advisor, while Debbie Fiderer is the President’s executive secretary and Amy Gardner is a domestic-policy strategist. Kate Harper is the one associated with Mary McCormack and the deputy advisor title.