Sikorsky VS-44A.

In 1940, American Export Airlines ordered 3 VS-44A's,
the Excaliber, Excambian, and the Exeter.
Dubbed the "Flying Aces", they were the world's longest
range airliner of the day and the only aircraft capable
of flying nonstop across the North and South Atlantic at
full payload.

The Excambian, here, is the only example remaining today.