The Khalkotauroi are mythical creature

Legendary creature

A legendary creature is a mythological or folkloric creature.-Origin:Some mythical creatures have their origin in traditional mythology and have been believed to be real creatures, for example the dragon, the unicorn, and griffin...

s that appear in the Greek myth

Greek mythology

Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

 of Jason

Jason

Jason was a late ancient Greek mythological hero from the late 10th Century BC, famous as the leader of the Argonauts and their quest for the Golden Fleece. He was the son of Aeson, the rightful king of Iolcus...

 and the Golden Fleece

Golden Fleece

In Greek mythology, the Golden Fleece is the fleece of the gold-haired winged ram, which can be procured in Colchis. It figures in the tale of Jason and his band of Argonauts, who set out on a quest by order of King Pelias for the fleece in order to place Jason rightfully on the throne of Iolcus...

. They are two immense bulls with bronze hooves and bronze mouths

Bull (mythology)

The worship of the Sacred Bull throughout the ancient world is most familiar to the Western world in the biblical episode of the idol of the Golden Calf. The Golden Calf after being made by the Hebrew people in the wilderness of Sinai, were rejected and destroyed by Moses and his tribe after his...

 through which they breathe fire. In the Argonautica, Jason is promised the prized fleece by King Aeetes

Aeëtes

In Greek mythology, Aeëtes , , , was a King of Colchis , son of the sun-god Helios and the Oceanid Perseis , brother of Circe and Pasiphae, and father of Medea, Chalciope and Apsyrtus...

 if he can first yoke the Khalkotauroi and use them to plough a field. The field was then to be sown with dragon's teeth

Dragon's teeth (mythology)

In Greek myth, dragon's teeth feature prominently in the legends of the Phoenician prince Cadmus and Jason's quest for the Golden Fleece. In each case, the dragon's teeth, once planted, would grow into fully armed warriors....

.

Jason survived the burning flames of the bronze bulls by smoking in a magical potion that protected him from the heat. The potion had been provided by Medea

Medea

Medea is a woman in Greek mythology. She was the daughter of King Aeëtes of Colchis, niece of Circe, granddaughter of the sun god Helios, and later wife to the hero Jason, with whom she had two children, Mermeros and Pheres. In Euripides's play Medea, Jason leaves Medea when Creon, king of...

, King Aeetes own daughter, who had fallen in love with Jason.

The Khalkotauroi were a gift to King Aeetes from the Greek God's blacksmith Hephaestus

Hephaestus

Hephaestus was a Greek god whose Roman equivalent was Vulcan. He is the son of Zeus and Hera, the King and Queen of the Gods - or else, according to some accounts, of Hera alone. He was the god of technology, blacksmiths, craftsmen, artisans, sculptors, metals, metallurgy, fire and volcanoes...

.

He Hephaistos had also made for him Aeetes king of Kolkhis Bulls with feet of bronze the Khalkotauroi and bronze mouths from which the breath came out in flame, blazing and terrible. And he had forged a plough of indurated steel, all in one piece." - Apollonius Rhodius, Argonautica 3.215

Film

• Nick Willing's version of Jason and the Argonauts features a creature known as the Menaian Bull, a somewhat part-bull part-machine, which Jason has to tame. This version, however, does breathe fire and is used to plow the fields by Jason.