Penelope Clearwater is a Ravenclaw student. During Harry's second year at Hogwarts, she was attacked by the Basilisk. She was also a Ravenclaw Prefect and said to be Percy Weasley's girlfriend.
From the story
Discovered in Book 2, Chapter 14, Cornelius Fudge
"Penelope Clearwater is a Ravenclaw Prefect. She is Petrified at the same time as Hermione."
Discovered in Book 2, Chapter 16, The Chamber of Secrets
"Penelope is tended to in the hospital wing along with the other Petrified students."