Shirley is four times the size of any other sheep. Being the fattest and laziest of the entire Flock, she has to be pushed around to go anywhere. Her appetite is utterly voracious, causing her to eat just about anything placed in front of her, edible or otherwise. Her enormous girth is not without merit, as she is often used as a battering ram or defensive wall when needed. This also results in her being the strongest member of the Flock. Many things are often stored in her fleece, and at times even misplaced in it. Shirley is also very wealthy, although the flock did not know it until the episode "In The Doghouse".
In "Shape Up with Shaun", Shaun puts her on a diet and severe exercise program, and for a while, she is slim and active. Unfortunately, she is immediately accidentally catapulted headfirst into a nearby pie van, where her appetite causes her to almost instantly regain all her previous weight.
Despite her peaceful outlook, Shirley can become highly aggressive, and angry if things may not turn out for her or if something goes wrong. It is revealed that in the episode "Foxy Laddie" in which The Fox dresses up like a sheep in which Shirley falls in love with. Upon realising that the sheep is actually The Fox, Shirley becomes angry and heartbroken. With the help of Shaun and the flock, he's able to corner The Fox in the local tools shed and Shirley ends up beating him up with a frying pan. This is seen again in the episode "Lockout" when Pidsley tries to scare off Shaun, but her big size overwhelmed the cat, and then he beats up Pidsley and nails him to a wall in underwear.
- Shirley can do cartwheels. The Flock didn't know it until "Hidden Talents".
- Unlike Timmy's mother and Lola, there are no obvious signs that Shirley is female, as her feminine name is never mentioned in-series. This combined with her deep baritone voice has lead people to assume she is male.
- Shirley isn't always greedy, as shown in "Happy Farmers Day" episode. Bitzer made a pie for the farmer and put it by the window to cool down, but Shirley noticed it and tried to take the pie, but the metal was too hot. Timmy showed Shirley some oven mittens, so she used them and put it inside the freezer, but Bitzer accused her of eating the pie, but Timmy reveals the pie was in fact in the freezer at the episode's end.
- Due to her size, Shirley very rarely walks on her hind legs. As such, instances of her using her hands for anything are far and in-between.
- In "Shape Up with Shaun", Shirley is briefly slimmed down by Shaun's extensive exercise regiment. During this time, she appears very similar to Shaun in build and appearance, although she retains her deep baritone voice despite the weight loss.
- In "Buzz Off Bees", she was first stung by the bees and in another episode in Series 4, "The Spider", she was afraid of a spider and screamed because of the spider in her front right hoof.
- In "Saturday Night Shaun", during the end, she eats a music player, making the flock want to dance.
- As seen in Weighlifting, one of the Championsheeps episode, we see that Shaun had to lift a weight that had Shirley on one side and two other sheep on the other side. As told above, Shirley weighs 26 bricks, which made the two sheep on the other side also weigh 26 bricks if the weight is balanced. Therefore, each sheep, except Shaun, Timmy and Shirley, weighs around 13 bricks.
Names around the World
- Japanese: シャーリー - Shārī
- Chinese: 雪莉 - Xuě lì
- Hindi: शर्ली - sharlee
- English: Shirley
- Korean: 셜리 - syeolli
- Finnish: Sirkka, originally Siiri
- German: Shirley
- Russian: Ширли