A Chief of Staff can be:

• The chief aide to the commander of larger military formations and units
• The professional head of a branch of the armed forces. The title comes from the fact that they are the chief military aides to the Commander-in-Chief, who is usually the head of state.
  • Joint Chiefs of Staff, a panel comprising the highest-ranking members of each major branch of the armed services in a country, particularly used in the United States
    • Chief of Staff of the United States Army
    • Chief of Staff of the United States Air Force
  • Chiefs of Staff Committee, the most senior military personnel in the British forces
    • Chief of the Defence Staff
    • First Sea Lord or Chief of the Naval Staff
    • Chief of the General Staff
    • Chief of the Imperial General Staff
    • Chief of the Air Staff
  • Ramatkal, or Chief of the General Staff, the highest ranking officer in the Israeli General Staff (the Israeli Defence Forces high command).
  • Stabschef, commander of the Nazi Sturmabteilung
• The chief aide to a political leader
  • White House Chief of Staff, the highest-ranking member of the Executive Office of the President of the United States
  • Chief of Staff (United Kingdom), the head of the Prime Minister's Office in the United Kingdom
  • Chief of Staff (Canada), the head of the Prime Minister's Office of Canada
  • Chief of Staff (Philippines), the head of the Office of the President in the Philippines
  • U.S. Congressional Chief of Staff, the head of the office of a member of the United States Congress

Stabschef