Jan Brady
Poor Jan: She suffers from middle child syndrome, always living in her sisters' shadow. Of course, most of Jan's paranoia is in her mind, though Marcia is a tough act to follow. Her buddy Lucy Winters accidentally calls Jan "Marcia" on a party invitation, and Jan thinks the solution is to get new hair. Of course, the hair isn't her problem at all -- everybody envies Jan's long, blonde locks.
Jan, like any insecure teenager, has to suffer through glasses and braces. She eventually gains confidence, and although she'll never be the cheerleader that Marcia is, she's liked enough to be voted most popular girl at Fillmore Junior High. Even though Jan has announced that she wishes she was an only child, she really loves all her siblings (including Marcia).