Shelby Cummings (Julie Gonzalo) is the secondary villainess of the 2004 teen movie A Cinderella Story. She was a popular high school student who used her wealth as an excuse to bully anyone outside of her clique. A big target of her bullying was Sam Montgomery, who was dubbed the nickname "Diner Girl" due to her working for her evil stepmother Fiona in her deceased father's diner. She was also the girlfriend of football star Austin Ames, though he did not approve of her callous ways and secretly wanted to leave her.
Shelby's first act of bullying against Sam was stealing a parking space from her at school and then loudly insulting her. On the night of their school's Halloween-themed homecoming, Shelby and her friends ate at the diner and Shelby acted condescending and rude towards Sam, calling her by her cruel nickname. Austin then shocked Shelby by trying to break up with her, but she refused to believe it to be true and left with her two female friends to get ready for the dance. At the dance, Shelby became jealous upon seeing Austin talking with Sam (who was in disguise for the dance). Later on, Austin's friend David tried to force himself on Shelby, but he was stopped by Carter Ferrell, Sam's best friend who had a secret crush on Shelby. The two then made out and Shelby seemed to develop an attraction, but she instantly rejected Carter once she learned who he was the following day.
After finding out Sam was "Cinderella" from her stepsisters Brianna and Gabriella, the evil Shelby exposed Sam's secret during a pep rally through a performance skit meant to humiliate and degrade Sam and her online relationship with Austin. Afterwards, Shelby believed Austin was going to take her back, but instead, Austin finally decided to go back to Sam. Shelby looked on with an upset expression as Sam and Austin made up with a kiss. The very end (in which Shelby unsuccessfully tried to hook up with Carter) also implied that Shelby and her clique lost their social standing after that.
- Julie Gonzalo previously portrayed high school bully Stacey Hinkhouse from the 2003 adaption of Freaky Friday.
- Shelby was one of the four villainesses who appeared in A Cinderella Story, the others were primary villainesses — wicked stepmother Fiona Montgomery (played by Jennifer Coolidge) and her daughters, Brianna and Gabriella Montgomery.