There is a species native to the planet Mars which is seen but never actually named or explained. Unlike most Martian races which, with the exception of the Clay People, are roughly human in appearance, these Martians have bulbous heads.
Two of them are beamed through millions of miles of space from Mars to Earth in order for the Nitron beam to drain all the nitron from the Earth's atmosphere. One of the Martians dies immediately on arrival, the other survives just long enough to complete the task. Queen Azura calls them 2 of her "most loyal subjects".
It is possible that they are normal Martians who were surgically enhanced in order to survive the trip through space. Alternatively, they may have been changed to this state by means of Queen Azura's magic, which was also able to transform Martians into clay.
However, other examples of this "bulbous-headed" species are subsequently glimpsed around Queen Azura's palace during the events seen in the serial Flash Gordon's Trip to Mars. One is seen standing behind Ming the Merciless in Chapter 204: Ancient Enemies, and in Chapter 209: Symbol of Death 3 of them report to their Queen in the throne room, only to be immediately dismissed when other more important matters require her attention.