Martians appeared as antagonists in the Twisted Tales Of Felix episode "Mars Needs Felix" and where depicted as extremely surreal and frightening aliens that did not appear to share a standard shape or form - with individuals displaying radically different designs and behavior.
Felix was kidnapped by the Martians when he was tricked into thinking he would get a free trip around the world (with meals included) - only to be catapulted into space via a flying saucer and transported to a fantastical version of Mars.
When Felix arrived the Martians tried to force him into slave-labor but he simply beat up their leader before making a rather speedy escape from the legions of angry soldiers that pursued him - during his trip across Mars Felix encountered an innumerable sea of nightmarish creatures that existed in a state of absolute chaos.
Felix was continually in danger of being eaten by the Martians, especially the infants, who seemed to have a taste for feline - however during the great battle Felix managed to ultimately escape Mars and with aid from a seemingly sentient representation of the moon began to literally sail back to Earth.