Kenneth Patrick O'Donnell was an American political consultant and the special assistant and appointments secretary to President John F. Kennedy from 1961 until Kennedy's assassination in November 1963. O'Donnell was a close friend of President Kennedy and his younger brother Robert F. Kennedy, and was part of the group of Kennedy's close advisers dubbed the “Irish Mafia.”
O'Donnell also served as an aide to President Lyndon B. Johnson from 1963 to 1965. He later served as an adviser to Robert Kennedy's 1968 presidential campaign.