Wilhelmina (Willie) Wiggins, called Ms. Wiggins by Anna, is the woman who lives in the large Wiggins Mansion at the Wiggins Estate. She has a horse named Picasso and owned a pony named Winston from her childhood until he died in Good-Bye Pony. She would ride Winston using a pony cart because she is not small enough to ride him otherwise.
She loves to draw and paint, and her large house is full of her paintings. She shares that in common with Anna. Anna first met her when she was riding her pony along trails in Wiggins Estate, despite the various 'No Trespassing' signs. Anna was afraid of her at first, but after they talked she and the Pony Pals became good friends. Ms. Wiggins helped to advocate for Anna by talking to her mother and teacher to get her help for her dyslexia. Ms. Wiggins understands Anna's struggles since she is dyslexic herself.