Tiffany Kilbourne is the 11-year-old middle sister of Shannon Kilbourne and Maria Kilbourne. She attends Stoneybrook Day School with her sisters. Tiffany is described as is tall with blonde hair, blue eyes, dark eyelashes, and high cheekbones.
She used to be quiet, but has now turned into a brat. She doesn't get along with Maria, doesn't do well in school, never does her homework, and her room is a pigsty. Tiffany takes up gardening as a hobby and is raising spinach in her garden.