<p>Supergirl is correct! She graduated from Midvale High School in
<i>Action Comics</i> #318 (November 1964).
</p><p>In the Silver Age, Supergirl was the first major character to actually have character development. She graduated from high school before any of the Teen Titans -- even before Peter Parker (he graduated in September 1965). Supergirl worked in secret for several years until Superman approved of her going public, changed her secret identity name from Linda Lee to Linda Danvers when she moved from the orphanage to a foster home, and then in 1964 graduated and began attending Stanhope College. I believe she was the first college-attending superhero, but I'm not positive on that point. And while other heroes had occasionally starred in two-part and three-part stories, Supergirl was the first character in the Silver Age to have a really long multi-part story: from Action #278 to Action #285 -- eight issues in all.
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