First officer may refer to:

• Chief mate, the second-in-command (usually) of a merchant ship
• First officer (civil aviation), the second pilot of a civil aircraft
• Executive officer (military), the second-in-command of a naval vessel
• The most senior civil service position in the United States Foreign Service, with responsibility for running an embassy under the authority of and reporting to the ambassador
• Air Transport Auxiliary rank corresponding to Flight Lieutenant in the Royal Air Force
• Women's Royal Naval Service rank corresponding to Lieutenant-Commander in the Royal Navy

• Navalmoral de Béjar, Salamanca
• Navalmoral de Béjar, Spain
• Navalmoral de la Mata
• Navalmoral de la Mata, Cáceres
• Navalmoral de la Mata, Spain
• Navalmoralejo
• Navalmoralejo, Spain
• Navalmoralejo, Toledo
• Navalmoral, Spain
• Navalmoral, Ávila
• Naval museum
• Naval Museum of Manitoba
• Naval Network Warfare Command
• Naval Nuclear Power Training Command
• Naval Observatory, District of Columbia
• Naval Oceanographic Office
• Naval Ocean Surveillance System
• Naval Officer
• Naval officer rank
• Naval officers
• Navalone
• Navalonguilla
• Navalonguilla, Spain
• Navalonguilla, Ávila
• Naval Operating Base, Norfolk