Maria is a little girl riding on a horse that helped Timmy get to the North Pole on Christmas. She only appears in the episode Christmas Everyday!.
She, along with many other children around the globe, had read Timmy's e-mail pleading for help saving Santa Claus. Later, she showed up at the North Pole with an army of kids to help Timmy and Santa defeat the Easter Bunny.
She wears pink cowgirl clothes, has blond hair in braids, and blue eyes with liner that resembles Trixie's.
Aside from briefly helping Timmy Turner along his journey to the North Pole, and then later showing up with an army of kids to help him, she has not done much else in the series.