Joog, otherwise known as the "giant man of mars", was created by the hormad scientist Pew Mogel to be an indestructible engine of war in his attempt to conquer Barsoom. Joog is one hundred and thirty feet tall and has a hairy face and two rows of teeth. He was constructed from corpses of ten thousand red martians and white apes, despite the fact that his brain is a composite of many martian brains he is seemingly unintelligent. In battle Joog wore a helmet that Pew Mogel sat in and controlled the giant, the giant himself used an uprooted tree as a weapon.
Joog was used by Pew Mogel to attack Helium. The Helium fleet tried to destroy him, but Joog regenerated his body faster than they could damage it. When John Carter killed Pew Mogel, he gets the microphone that controls Joog's actions and orders him to retreat back to Korvas. What happened to him after this is unknown.