To clarify, she is the classic tsundere. The modern tsundere archetype is completely different from what the original term meant in the good ol' days.
Peace.
I loved the oragne road manga.
are you sure about her being the prototype? it seems a bit weird to imagine there being a prototype for such a broad character archtype..
@Munsu: The anime and its OVAs and movies are fine, I just feel that the manga holds itself up better, as well as simply being easier to go through, since you don't have to worry about the release schedule at all. It's just a straight run through.
@Death Boo: That seems to be the consensus, she's the source of the archetype. That's not to say there aren't other contenders. Kitajima Maya from Glass Mask (and that one is from her perspective!), Otonashi Kyouko from Maison Ikkoku (though she fills a bit of a different niche imo), or Tendou Akane from Ranma.
I wouldn't call her a "prototype," since she's also one of the best examples of one that is more than a cardboard cutout of the "modern tsundere" and has some real humanity backing up her attitude. It's more that Madoka is very specifically that cold or brusque exterior hiding a very vulnerable and loving interior. There's a reason behind every way she acts, relatable and realistic.
It's not something the other three above share. Akane doesn't soften until well into the series, Kyouko is really just a fountain of jealously (more of a Narusegawa Naru type tsundere), and Maya doesn't really fit the mold because you see her personality develop from her perspective, not her love interest's.