A viper; serpent.
And the sucking child shall play on the hole of the asp, and the weaned child shall put his hand on the COCKATRICE' den. They shall not hurt nor destroy in all my holy mountain: for the earth shall be full of the knowledge of the LORD, as the waters cover the sea. ( Isaiah 11:8-9 )
Bibliography Information"Entry for 'Cockatrice'". A King James Dictionary.