Gockos are the fierce fire Dragons of planet Mongo. They resemble conventional Dragons, aside from their tendency to walk on hind legs - the number of which ranges from two to six - using a stiff tail as a counterbalance, their forehead horn which branches in two, and their massive crustacean-like claws. The bumpy rubbery multicolored flesh is also noteworthy.
One lived in the Tunnel of Terror guarding the entrance to the Sacred Temple of the Great God Tao. Every night at the sacred hour of midnight it fell into a deep sleep which could only be awakened by the Gocko Gong. Flash Gordon encountered it once, while trying to get to Emperor Ming and Dale Arden’s wedding to break it up. On that occasion it did not interpret him as a threat, and opted not to waste its flames. The Gocko was strangling him in its claw and about to snap him in half, when Prince Thun rushed in and shot it in the face, incapitating it for a few hours.
Later, when the Gocko was asleep, Princess Aura, the Mongo High Priest and an escort of soldiers were carrying the drugged Flash into the Tunnel of Terror to get to the Temple, when the Priest proved traitorous and sounded the gong. Fortunately Flash’s friends were in pursuit, and Dr. Zarkov saved her by throwing a grenade at the monster. The Gocko had been considered sacred and its death threw the palace into chaos.