Basilisk

Folklore holds that,much like the cockatrice, the first basilisks hatched from eggs laid by snakes and incubated by roosters, but little in the study of Basilisk, lends any credence to this claim.

The Basilisk often called the "King of Serpents," is in fact not a serpent at all, but rather an six-legged reptile with a nasty disposition and the ability to turn creatures to stone with their frightening gaze. Basilisks live in nearly any terrestrial environment, from forest to the deserts, and their rough hide tend to match and reflect their surroundings.

An adult basilisks is 14 feet long, with fully half of that made up by its long tail, and weigh 350 pounds.

Ironically I like to think of it being part rooster