"Are you insinuating that moi took Wallabee's homework?"-- Valerie
Valerie is a school rival of Numbuh 5 and a favorite of their teacher, Mrs. Thompson. She is the main antagonist in Operation: H.O.U.N.D., and Operation: D.O.G.H.O.U.S.E.. In Operation: H.O.U.N.D., Numbuh 5 is attacked by a monstrous poodle while walking past Valerie's house on the way to school, and claims that Valerie's dog ate her homework, to which Valerie denies, claiming her dog is a harmless puppy. Later, she, Numbuh 2 and Numbuh 4 sneak into Valerie's house to investigate, and find her pet dog, who is indeed a small puppy as she said.
When Valerie discovers them, it is revealed that she can transform into a "Were-poodle" and that she was the monster who ate Numbuh 5's homework. At the end of the episode, Mrs. Thompson arrives on the scene and scolds Valerie for letting her secret be revealed, as they both transform into weredogs, explaining their unusual relationship.
- She bears a resemblance to Emily Elizabeth from Clifford the Big Red Dog. They are both voiced by the same voice actress and have the same clothing although Emily doesn't have pigtails like Valerie.
- Coincidentally, they both have pet dogs.