Airbus A380 planes

Once it enters service, the A380 will become the world's largest airliner and at least the second largest plane. Additional stretched models are also planned, and one of these will almost surely supersede the An-225 to take the official title as world's largest plane.

Your question also mentions two other classic aircraft that were certainly enormous by any measure. Unfortunately, both proved to be disastrous follies that were great embarrassments to their proponents. The Spruce Goose, officially known as the Hughes H-4 Hercules, was the brainchild of flamboyant billionaire Howard Hughes.

The aircraft had originally been ordered by the US government during World War II as a giant cargo plane ferrying up to 750 armed troops or two 30-ton tanks. As the war concluded, Hughes believed he could adapt the massive plane to revolutionize long-distance transportation in the fledgling airline and air cargo industires.

His creation was the world's largest plane at the time and is still the largest flying boat ever built with a maximum takeoff weight of 400,000 lb (180,000 kg). The enormous craft also holds records for the largest wingspan at 319 ft 11 in (97.5 m), tallest airplane at 79 ft 3 3/8 in (24.2 m), and the largest aircraft ever made from wood.