Aero Spacelines Inc. was an American aircraft manufacturer from 1960 to 1968 that converted Boeing 377 Stratocruisers into the famous Guppy line of airplanes, re-engineered to transport oversized cargo such as space exploration vehicles.

The Boeing 377 Stratocruiser was a large long-range airliner developed from the C-97 Stratofreighter military transport, itself a derivative of the B-29 Superfortress. The Stratocruiser's first flight was on July 8, 1947. Its design was advanced for its day; its relatively innovative features included two passenger decks and a pressurized cabin. It could carry up to 100 passengers on the main deck plus 14 in the lower deck lounge; typical seating was for 63 or 84 passengers or 28 berthed and five seated passengers.