The Douglas DC-8 is a four-engine jet airliner, manufactured from 1958 to 1972. Launched later than the competing Boeing 707, the DC-8 nevertheless established Douglas in a strong position in the airliner market, and remained in production until 1972 when much larger designs, including the DC-10, made the DC-8 obsolete. Relegated to second-line duties, details of the DC-8 design allowed it to hold slightly more cargo than the 707; hundreds of re-engine examples remain in freighter service to this day, while commercial 707 service had largely ended by 2000.

Boeing's plans became obvious in the industry, in spite of their "code name" intended as a disinformation tactic. Douglas secretly began jet transport project definition studies in mid-1952. By mid-1953 these had developed into a form very similar to the final DC-8; an 80-seat, low-wing aircraft with four Pratt & Whitney JT3C turbojet engines, 30-degree wing sweep, and an internal cabin diameter of exactly 11 feet (3.35 m) to allow five abreast seating. Maximum weight was to be 95 tons, and range was estimated at somewhere between 3,000 and 4,000 miles (4,800 to 6,400 km).