A cockatrice is a mythical beast, essentially a two-legged dragon or serpent-like creature with a rooster’s head. A cockatrice was a magical beast resembling a rooster with a lizard’s tail. The Cockatrice can cause death with a single glance. Their poisonous saliva can even kill an elephant.
This definition is what the world thinks a cockatrice is, but Isaiah refers to it three times and says it will exist during the 1000 years of peace on earth.
Isaiah 11:8 And the sucking child shall play on the hole of the asp, and the weaned child shall put his hand on the cockatrice’ den.
Isaiah 14:29 Rejoice not thou, whole Palestina, because the rod of him that smote thee is broken: for out of the serpent’s root shall come forth a cockatrice, and his fruit shall be a fiery flying serpent.
Isaiah 59:5 They hatch cockatrice’ eggs, and weave the spider’s web: he that eateth of their eggs dieth, and that which is crushed breaketh out into a viper.