Ekranoplan Casspian The Russian Tank-Ship-Plane. Not exactly a plane but still cool. It flies just over the water because of ground effect. So it can haul a heavy load very efficiently compared to getting it up to altitude. Or floating.
Mikoyan-Gurevich was a Soviet interceptor and fighter aircraft used during World War II. It had been designed for high-altitude combat but combat over the Eastern Front was generally at lower altitudes where it was inferior to other Soviet fighters.