| The name of this article was obtained from production material.
While the name is technically official, a future episode can give the character a new name, which will then become the official name.
- For other uses of "Mary", see Mary (disambiguation).
|Book debut||Arthur's Off to School|
|Cartoon debut||"Arthur's Eyes"|
The first time she spoke was in the episode, "Arthur's Substitute Teacher Trouble" as she spoke to one of her classmates and most likely friends, 3rd Grade Male Dog about the clouds in the sky. The second time she spoke was in the episode, "Buster Baxter, Cat Saver" and the third time took place in the episode, "Arthur and the Square Dance" when she said "Whoahh!" during the square dance at the school as she and the entire class fell to the ground, and the fourth time in "The Lousy Week". She is relatively a nice student as seen in many episodes.
Mary is a sheep with a cream complexion. She wears a light gray turtleneck, a light yellow sweater over the turtleneck, dark yellow shorts, gray belt, yellow belt buckle, and brown loafers. She has blonde hair. In the episode, "D.W. Swims with the Fishes" she wore a light blue colored swimsuit.
Yeah, it's so cute.
|—Mary describing a bunny-shaped cloud, "Arthur's Substitute Teacher Trouble"|
I just love Buster-sicles
|—Mary, "Buster Baxter, Cat Saver"|
Oh, it feels so expensive!
|—Mary describing Muffy's hat, "The Lousy Week"|
Welcome, Arthur's sister!
|—Mary to D.W., "Francine's Big Top Trouble"|
(gasp) "Let's get out of here! This place is weird."
|—Mary, Arthur and the Haunted Treehouse|
- Mary is currently the only sheep character that has made regular reappearances in the series.
- She has a one-time doppelganger, Unknown Male Sheep. This is similar to Beulah McInnerny and her doppelganger, Aloysius Zimmerplotz.
- She is in Miss Sweetwater's class.
- Her name is likely a reference to the nursery rhyme Mary Had a Little Lamb.
- Her name was never said on the show, but it was on her character modelsheet.
Mary has made several appearances throughout the series. The episodes where she has had a major role are in bold.