In the 1920’s newly hired engineers at General Electric would be told, as a joke, to develop a frosted lightbulb. The experienced engineers believed this to be impossible. In 1925, newly hired Marvin Pipkin got the assignment not realizing it was a joke and succeeded.
The engineer who designed the Japanese Kamikaze dive-bombing planes of WWII felt bad about his role in the war, so at its end, he decided to use his skills for peace by designing the body of the Shinkansen (Bullet Train), which has, to this day, operated with zero accident-caused fatalities.
A man named Roger Boisjoly and his colleagues attempted to stop Challenger from lifting off into space knowing that a disaster would happen, but ultimately failed.