The Khalkotauroi (tauroi khalkeoi, "bronze bulls") are mythical creatures that appear in the Greek myth of Jason and the Golden Fleece. They are two immense bulls with bronze hooves and bronze mouths through which they breathe fire. In the Argonautica, Jason is promised the prized fleece by King Aeetes 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.

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, 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.

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