The legendary (not really) JF2 Duck. It could land on land, sea, and aircraft carriers. It was used by the Navy, Marines, and Coast Guard as a search, rescue, reconnaissance, and even supply plane.
When the Navy abandoned a base in the Philippines, the Army repaired a damaged Duck the Navy left behind. They used it against the Japanese and flew some wounded servicemen to Australia just before the Philippines fell.
After WW2, the newly-formed US Air Force used some for rescuing downed pilots from training missions.
Although obscure, the Duck is considered one of the finest multi-purpose planes ever built.