Wendy, a "superhero-in-training" with along with Marvin and Wonder Dog, were the Super Friends' first set of audience surrogate sidekicks, which were seemingly insisted upon at the time. Nobody liked them and they were quickly replaced with the Wonder Twins. Later, they were given somewhat more interesting material to work with, Wendy in one incarnation later becoming an Amazonian teacher, and another... getting mauled by Wonder Dog, leaving her paraplegic and backing up Oracle... jeez.