What about Enabran Tain, a man who worked tirelessly for the advancement of Cardassia, sacrificing a personal life or any normality for the cause he believed in?
Ah, but that cause was not a healthy one. Unrepentent leaders of brutal "secret police" organizations who try to commit genocide, drag their nations into wars with foreign powers and assassinate their own children to facilitate their return to power aren't going to make the list, I'm afraid
. This is for people who worked to better Cardassia, as in truly better it, break it out of the system it had caught itself in. Tain is the sort of person Ghemor and Lang were trying to free Cardassia from; he's the antithesis of a Cardassian hero.
Tain's selflessness- and, yes, with the exception of his desire to drag his son into his dark OO world Tain was
selfless- was of the deeply unhealthy and twisted variety that set Cardassia on the path towards destruction. Tain is no hero; he's one of the "night people", as "A Stitch in Time" puts it. He thought his allegiance was to Cardassia, but instead it was simply to the secrets. Yes, he sacrificed a normal life- but for what? To become an avatar for everything that was wrong with Cardassia in the first place, to take his people's fears and contain them, lock them down rather than dealing with them, until he became nothing but a vessel for those fears himself. There's nothing left of him, only night...