Okay, since the question of "which female TMNT character would you bring back to the franchise if you could?" has been making the rounds (though mostly as an unspoken question to respond to the producer of the Nicktoons show stating there were enough female characters already) I'll suggest Quarry.
However, I'd be scared that any re-visiting of Quarry would get rid of what makes her special, and my very specific ideas about these things would probably make any desire for a revival meaningless.
Quarry appeared in the 4Kids cartoon as a human who had been mutated into a genetically-engineered creature suitable for digging through tunnels to find the TMNT's lair, before she and the other subjects rebelled. She and her comrades had two story arcs, which ended with being permanently restored to human form and going to the surface.
Because her mutated form had a deep, masculine voice (courtesy of a pitched-down Eric Stuart) and she could not remember anything about herself, Quarry was referred to as a male character until her first transformation to a human revealed the truth.
While Quarry had the most lines out of all the creatures and was their leader, she was also extremely fearful at times, but overcame her fear as often.
I never liked the "Oops, a girl!" surprise, because it added nothing to the story, and downplays the idea that we have one of the few female mutants in the franchise. Plus, Quarry's form looked adequately feminine in comparison to her counterparts already, so there was no further need to mistake her for male.
The only thing I can see is that Quarry's assumed male gender allowed the writers to get away with showing her be borderline cowardly at times, jumping at shadows and afraid to be left alone. Which is a fair thing to assume, and it would look worse for a female character to be written that way, because of the baggage involved.
IF there were a Quarry who was presented as female from the start, that aspect of her would have to be toned down, BUT not gotten rid of. I'm not saying that female characters can't be fearful, just that we're not at the point where these things are equal.
Yet Quarry overcoming her fear is an important part of her character, and the aspect that really made her stand out.
I also would hate to see any theoretical Quarry revival have a prettied-up monster form, including eliminating her acid-drooling ability. I think it's good to have female characters who aren't traditionally attractive, who are aliens, monsters, and freaky things. The aversion to such is probably why most female TMNT characters are human, but I'd like to see that changed.
