Basilisk

The Basilisk was a giant serpent, also known as the King of Serpents. It was a magical beast that was bred usually by Dark Wizards. Herpo the Foul was the first to breed a Basilisk; he accomplished this by hatching a chicken egg beneath a toad which resulted in the creature known as a Basilisk.[3] Basilisk breeding was banned in Medieval times. The practice could be hidden when the Department for Regulation and Control of Magical Creatures came to check by simply removing the egg from the toad.[2] Looking a Basilisk directly in the eye caused instant death, but an indirect look would merely render the victim Petrified.[3] It was also the mortal enemy of spiders, who could intuitively sense them and flee whenever they did.[4] The Basilisk had a classification as an XXXXX creature, meaning it was a known wizard-killer that couldn't be domesticated due to its immense powers.[2] However, since the Basilisk was still a serpent, a Parselmouth might communicate with it and potentially place the creature under their influence.[2][1] This depended on the relationship between the Basilisk and the Parselmouth. Tom Riddle was the only one who could command Salazar Slytherin's Basilisk, while Harry Potter had no control over it.[1]