Mrs. Tibble

' Mrs. Tibble''' is Tommy and Timmy Tibble's paternal grandmother.

Appearance
Mrs. Tibble is a bear depicted with a brown complexion, gray hair worn in a bun, and wears a bluish-green dress, a white shirt, a pink button-up shirt, and pink high-heeled shoes. When she first appeared in the book Arthur's Halloween that was first published in 1982, and returned in the 1992 book Arthur Babysits, she and the Tibble Twins were humans although they later became bears for the cartoon, but they're still humans in the later books.