The MD-12 was a concept airliner proposed in the early 1990's. It was intended to be a competitor for the double-decker Airbus A380 (known as the A3XX at the time). Physically, the mockups and renderings of the MD-12 looked almost identical to the current design of the A380.

McDonnell Douglas was bought out by Boeing while the MD-12 project was still on the drawing board. Rather than continue the MD-12, the company decided to concentrate on new versions of the Boeing 777 and Boeing 747, leaving Airbus Industrie a virtual monopoly on the ultra-high-capacity passenger aircraft market, and leaving the MD-12 a footnote in aviation history.