Who was nicknamed Fighting Joe in the American Civil War?

Major General Joseph Hooker and also Lieutenant-General Joseph Wheeler.
Joe Hooker.

It happened by mistake - there was a section in some document headed 'Fighting', followed by 'Joe Hooker', but the name stuck.

Curiously, it was not viewed as a compliment. It was taken to indicate unseemly brawling, and Hooker did not appreciate it.