Scrawny, young brown mouse, blue eyes (originally), heterochromia (blue left eye and green right eye) (In The Sequel), pink bow on head, purple dress with lilac vest and a dark purple patch on the skirt (As A 12 Year Old), light blue apron (in laundry scene), barefoot, purple dress with a violet shirt and white apron and collar (As A 15 Year Old)
Teresa is 11-12 years old (by human age) and holds part of the responsibility of the Brisby household. She is responsible and mature for her age.
Role in film
Teresa Brisby is the eldest child of the Brisby family. She helps Auntie Shrew take care of the household while her mother is gone. She is very beautiful, cute, kind, and sweet, though she dislikes it when her younger brother Martin fights or argues with Auntie Shrew.
Teresa in the original film had blue eyes like her mother, but in the other films, she possesses heterochromia which is odd as her father had brown eyes, so where she inherited her green eye is unknown.