The McDonnell Douglas YC-15 is a replaced prototype four-engine short take-off and landing (STOL) tactical transport. It was McDonnell Douglas' entrant into the United States Air Force's Advanced Medium STOL Transport (AMST) competition to replace the Lockheed C-130 Hercules as the USAF's standard STOL tactical transport. In the end, neither the YC-15 nor the Boeing YC-14 was ordered into production, although the YC-15's basic design would be used to form the successful McDonnell Douglas C-17 Globemaster III.

McDonnell Douglas Corporation was a major American aerospace manufacturing corporation and defense contractor, formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967. Between then and its own merger with Boeing in 1997, it produced well-known commercial and military aircraft, such as the DC-10 and the MD-80 airliners, the F-15 Eagle air superiority fighter, and the F/A-18 Hornet multirole fighter.