Yeah but the duck is pretty well known.
How about the LEGO Gun toy.
Its called Halvautomatisk Legetöjspistol, made between 1945–1949, features a spring-loaded mechanism that could feed projectiles into the barrel from a magazine, allowing rapid firing.
Or the father of all LEGO minifigures, Ringfigure .
And who could forget LEGO Klodser set.
NO, surprisingly it was the Yo-Yo.
Made 3 years before the famous Duck.
(Somehow, Im glad the family factory burned down and made them start all over with only plastic brick sets afterwards).