18 Squadron or 18th Squadron may refer to:
- No. 18 (Netherlands East Indies) Squadron RAAF, a unit of the Royal Australian Air Force
- No. 18 Squadron IAF, a unit of the Indian Air Force
- No. 18 Squadron RAF, a unit of the United Kingdom Royal Air Force
- 18th Squadron (Observation), a unit of the United States Army Air Service
- 18th Aggressor Squadron, a unit of the United States Air Force
- 18th Combat Mapping Squadron, a unit of the United States Army Air Force
- 18th Intelligence Squadron, a unit of the United States Air Force
- 18th Flight Test Squadron, a unit of the United States Air Force
- 18th Reconnaissance Squadron, a unit of the United States Air Force
- 18th Space Defense Squadron, a unit of the United States Space Force
- 18th Squadron (Belgium), a unit of the Belgian Air Force
- Marine Wing Communications Squadron 18, a unit of the United States Marine Corps
- Marine Tactical Air Command Squadron 18, a unit of the United States Marine Corps