As I mention I'm a different thread here, there were some tentative plans to bring Mudd back in the first season of TNG (found frozen in a statis pod floating in space) and at the end of the episode he would have been given a choice between saving the Enterprise, or some kind of large wealth, and according to what I read (I believe in Star Trek: The Official Fan Club Magazine) he would have at the very last minute (a bit reluctantly) saved the Enterprise, and said something like "This one's for Kirk and Spock!'
Unfortunately the actor, Roger C. Carmel, passed away in late 1986.
Also, this would have violated Gene's rule about NOT mentioning Kirk and Spock, but I gathered this was more of an idea floating around the writer's room than a fully polished script.
But it certainly would have been a HECK on an episode!! And it would have fit much more with the semi-reformed lovable rogue version of the character, not so much the bloodthirsty killer. Too bad it was never made.