Penny's Sister is a minor character in The Amazing World of Gumball. She first appeared for a brief moment in "The Family Battle" during the chase scene. She makes another appearance in "The Welcome to Fitzgeralds," along with the rest of her family, this time with a larger role - she makes a tribute picture of Mr. Cuddles, her family's pet. When she shows Gumball the picture, he gets scared of it and stomps the picture to the ground, causing her to start crying and upsetting her family.
She is somewhat similar to her older sister, Penny Fitzgerald, in appearance. She is half the size of her big sister, and has a body shape similar to an hourglass. She is also the only member of her family to not wear any type of footwear.