The Rock Men are a race seen in the third Flash Gordon film serial, Flash Gordon Conquers the Universe.
The region known as the Land of the Dead on the planet Mongo is believed to be uninhabited by any intelligent races, largely due to the dangerous magnetic properties of the underlying rocks and also because of the deadly iguanthions which roam the area.
Rumors have persisted, however, that a race of "rock people" used to inhabit the area, rumors which reached the ears of Prince Barin of Arboria among others. When Barin visits the area with his friends Flash Gordon and Dr. Hans Zarkov with a view to using Zarkov's Nullitrion device against Ming the Merciless, he learns that the rumors are not only true but that the Rock Men still exist.
A primitive tribe compared to other societies on Mongo, the Rock Men are actually very human-like in their appearance but dress themselves in rock-like garments in order to camouflage themselves. This acts not only as a safeguard against ending up as an iguanthion's lunch, but also allows them to spring surprise attacks when out hunting.
The Rock Men appear to worship some form of deity whose identity is unknown (but may be Great God Tao, venerated by others on Mongo) as they are prepared to offer sacrifices to it when the need arises. Their social structure is a simple one, obeying their designated leader the Rock King. His son, the Rock Prince, appears to have superior status, and wears a sun emblem on his chest.
They dwell in caves, and have no advanced technology, but have adapted to their environment well. They know how to produce healing vapors from the rocks.
Mistrustful of strangers (and with good reason when a party led by Officer Torch sets off a huge explosion in their area), they are honorable enough to pay back a good deed, such as when Flash Gordon rescues the Rock Prince when he becomes trapped by an exposed lodestone. The Rock Prince subsequently helps Flash to capture the escaping Captain Torch.
Unlike other races on Mongo, the Rock Men do not speak English. However, they share the same language as lost tribes which used to inhabit the Gobi Desert on Earth, which leads Dr Zarkov to speculate some common ancestry between the peoples of Earth and Mongo.