The Boeing KC-135 Stratotanker is an American military aerial refueling aircraft that was developed from the Boeing 367-80 prototype, alongside the Boeing 707 airliner. It is the predominant variant of the C-135 Stratolifter family of transport aircraft. The KC-135 was the US Air Force’s first jet-powered refueling tanker .

The KC-135 entered service with the United States Air Force (USAF) in 1957; it is one of six military fixed-wing aircraft with over 50 years of continuous service with its original operator. Studies have concluded that many of the aircraft could be flown until 2030, although maintenance costs have greatly increased.