In Harry Potter and the Chamber of Secrets, Harry Potter and Ron Weasley run into Penelope while sneaking around Hogwarts School of Witchcraft and Wizardry while disguised as Gregory Goyle and Vincent Crabbe. She is described as a black-haired Ravenclaw prefect, although she is not specifically identified until later in the book after she and Hermione Granger are petrified by the monster roaming the school.
It is later inferred that Penelope was wandering the halls the night Harry Potter met her in order to meet with her secret boyfriend, Percy Weasley, a Gryffindor prefect.
Penelope Clearwater was briefly seen the movie Harry Potter and the Chamber of Secrets when Nearly Headless Nick greets her and Percy Weasley in a hallway. She was played by Gemma Padley.