Not every every rejected Legion applicant goes on to join the Substitute Legion. Some, consumed by bitterness, turn to villainy. Such was the case with Sussa Paka, also known as Spider Girl:
After failing to gain entry to the Legion of Super-Heroes, Spider Girl went on to join the Legion of Super-Villains.
And that's pretty much the extent of what I knew about her. She was never a particularly major character, though apparently she got a little more focus during the Five Years Later period of the Legion, which I've never read. According to Wikipedia, she dyed her hair - which is super-strong and prehensile - blue and changed her name to Wave.
I imagine that the name-change was a nod to DC's Marvelous Competitor.
Speaking of Marvel, being a redhead with super-strong prehensile hair makes her largely indistinguishable from the Marvel character Medusa, of The Inhumans.
Honestly, if I took the spider web out of the background - is it clear that the web is composed of her hair? - I could just as easily say this is a picture of Medusa.
In any case, apart from (probably) reading the story of her failed application to the Legion in a reprint (and then, more recently, in one of the volumes of Showcase Presents: The Legion of Super-Heroes, and seeing her listed in the LSV's entry in Who's Who in the DC Universe, there's only one story in which I'd ever seen her appear. That particular story is actually one of my all-time favorites, though that really has nothing to do with Spider Girl...