The Serpent of Slytherin was a female Basilisk placed by Salazar Slytherin as the only resident of the Chamber of Secrets at Hogwarts School of Witchcraft and Wizardry, and the main antagonist in both the novel and film versions of Harry Potter and the Chamber of Secrets. The Basilisk could only be controlled by the heir of Slytherin, Tom Riddle. This meant that despite her being a Snake, other Parselmouths (such as Harry Potter) had no control over her, though they could still understand her.