This could be said of The Rogues because they have a code of "ethics" that they live by and consider themselves above killing women and children. Captain Cold is a particular stand out in this regard. This is also the reason they generally keep to themselves and don't work with the Secret Society; they're so stubborn and honor-bound that more amoral villains like Lex Luthor can't manipulate them, and instead alienate them by proposing schemes that none of the Rogues can stomach.
Hellblazer's succubus Chantinelle (Ellie) is less noble than extraordinarily unlucky. Having tried to seduce an angel and succeeded, she fell in love with him and bore his child, leading to his demise at the hands of other angels and her exile from Hell. John Constantine notes that she's not a bad sort considering what she actually is, to which she replies, "I don't think so, John...I think I'm just polite."
Neil Gaiman often writes to this trope. Denizens from Hell can often be bargained with (after all, being a demon is all about lying, backstabbing, betrayal, and personal gain) or reasoned with, and frequently have a code of honor by which they will abide, to the extent of helping out a protagonist. Lucifer in the earlier Sandman arcs is particularly representative of this trope.
The Secret Six sometimes fall into this, though it's usually more a case of punishing the evil (with torture) than saving the good. One of the best examples is Deadshot's revenge mission to a North Korean political prison.
Batman: Lady Shiva: She has a personal code of honor and a warped sense of loyalty. Good luck trying to predict what situations that code applies to, though.
Ra's Al-Ghul: Pun inside, he has a code of honor which he adheres by.
In Superman: Space Age, Brainiac, of all entities, is concerned with saving the multiverse by extracting all the worlds' best heroes in a chance at stopping the Crisis. When Superman and the League fight him to a stalemate, he withdraws, and decides not to destroy Earth because it would lessen Superman's chances of joining him.
