Various magical creatures play significant roles, both thematically and in terms of plot. Most notably, a giant serpent known as a basilisk serves as the mechanism by which Slytherin and Riddle seek to rid the school of Muggle-born students. The basilisk’s most potent weapon is its arresting stare, which can kill in an instant. The basilisk thus embodies and represents the violence that arises from those who see with eyes of hate.

Several creatures appear in direct contrast or opposition to the basilisk. Spiders are known to fear the basilisk; even the enormous Aragog and his colony of giant spiders refuse to speak of it. Spiders—a common target of fear and disgust among humans such as Ron—fear the basilisk, making it a kind of “monster Voldemort” in Harry’s view. Additionally, under Riddle’s control, Ginny kills several roosters, whose crowing threatens the basilisk, suggesting that if something as ordinary as a rooster could carry the key to a basilisk’s defeat, Voldemort may be similarly vulnerable to the attacks of a regular person like Harry. Finally, Fawkes, Dumbledore’s phoenix, opposes the basilisk, both in head-to-head combat and in restoring Harry to health after the basilisk wounds him. Known for their ability to be reborn after burning up, the phoenix symbolizes hope and Harry’s loyalty to Dumbledore.