A male individual of the Flying Wyvern species known as "Rath," clad in red scales. The green female individuals are distinguished as "Rathian." He constantly flies at high altitudes to watch over his territory, making it his duty to eliminate other species or monsters of the same kind that intrude. He is extremely ferocious with a strong sense of territoriality, showing no mercy to any monster that enters his domain. Possessing high combat capabilities, he has been observed fighting on equal terms with other large monsters and often reigns at the apex of the local ecosystem. He is carnivorous. His diet is broad; he preys on herbivores and Bird Wyverns, and sometimes catches aquatic animals like Epioth. As mentioned, he has been seen catching small birds as well as preying on flying creatures of his own size. He is capable of grabbing a full-grown Aptonoth in his talons and flying back to his nest, or even lifting large monsters into the air, indicating that the muscular strength of the wings supporting his massive body has considerable power to spare. He is extremely ferocious with a strong sense of territoriality, showing no mercy to any monster that enters his domain. Possessing high combat capabilities, he has been observed fighting on equal terms with other large monsters and often reigns at the apex of the local ecosystem. Due to these characteristics, he is known by the monikers "King of the Skies" and "Lord of the Heavens," and is also hailed as the "King of the Flying Wyverns" due to the high danger level resulting from his brutality, skill, and wide habitat range.

Like Rathalos, she is a type of Flying Wyvern known as "Rath," belonging to the order Saurischia, suborder Theropoda, infraorder Scutosauria, superfamily Psittacosauroidea, and family Rath. Rathian refers to the female of the species. She stays on the ground to guard the nest and eggs, so she does not fly often. Naturally, if eggs are stolen from the nest, she is the first to attack. While she does not fly much, her leg strength is highly developed, and she excels in physical combat such as biting and charging. Her destructive power is a major threat, often forcing inexperienced foes into a purely defensive position. For this reason, she holds the moniker "Queen of the Land." In contrast to Rathalos, who has poison in his talons, she possesses poison in the spikes on her back and the tip of her tail. Like Rathalos, she breathes fire. Her role is to protect the nest from the ground. Her reproductive form is oviparous. She lays about 5 to 10 eggs in a mortar-shaped nest built by the Rathalos. Rather than searching for a male herself, she waits in the nest for a male to arrive, and once one does, they begin their life together.