Missy is a puppy that appears in the book 101 Dalmatians: Proud to Be a Pup.
When the other puppies are telling tales of defeating Cruella De Vil, they tell Missy she sits in the back due to not being noisy. Due to this, she tries to be a cat with help from Sgt. Tibbs, but ends up finding herself doing canine-like things. She is put in the garden, which is where she notices Horace and Jasper. Thinking they are there to abduct the puppies again, Missy is able to send Horace and Jasper away by finally barking. Though still being sweet and quiet, all the puppies want to play with her now, and she is happy with being a Dalmatian.
In Proud to Be a Pup, Missy has one black ear and one white ear, which has a spot on it, and a noticeable spot on her muzzle.
Missy also appears in Rolly's Special Spots, in which she claims to have a spot shaped like one of Roger's slippers. However, both of her ears are white and, outside of a spot on her body resembling one of Roger's slippers, she is also shown with three spots on her right cheek.