Messerschmitt Me264 two Engines - only 3 prototypes were built with the intention of flying as far as New York but they had to drop the project to concentrate on fighters. The first flight was in 1942 , the project was cancelled in 1944.
The largest piston-engine land-based transport aircraft ever built Convair XC-99 was basically a military transport, but a passenger version was also proposed (Convair Model 37, good for 204 passengers):
Horten Ho 229 was a German prototype fighter/bomber designed by Reimar and Walter Horten and built by Gothaer Waggonfabrik late in World War II. It was the first pure flying wing powered by a jet engine.