A male individual of the Flying Wyvern species known as "Rath," clad in a red shell. The green female individuals are distinguished as "Rathian." He constantly flies at high altitudes to patrol 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, attempting to mercilessly drive out any monster that enters his domain. His combat ability is high, and he has been observed fighting on equal terms with other large monsters, often reigning as the apex predator of his region's ecosystem. He is carnivorous. His diet is broad; he preys on herbivores and Bird Wyverns, and has even been seen catching aquatic animals like Epioth. As mentioned, he has been observed catching small birds and preying on flying animals of his own size. He is capable of grabbing a full-grown Aptonoth in his talons and flying back to his nest, and can even lift large monsters into the air, suggesting his wing strength has considerable power to spare. He is known by the nicknames "King of the Skies" and "Lord of the Heavens" due to these characteristics. Because of his ferocity, skill, and high danger level combined with his wide habitat range, he is also hailed as the "King of the Wyverns."

Like Rathalos, she is a type of Flying Wyvern belonging to the Rath family. Rathian refers to the female of the species. She does not fly often, as she stays on the ground to guard the nest and eggs. Naturally, if you steal an egg from the nest, she will be the first to attack. Instead of frequent flight, 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 bears the nickname "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 primary role is protecting the nest from the ground. Her reproduction is oviparous. She lays about 5 to 10 eggs in a bowl-shaped nest built by the Rathalos. Rather than searching for a male herself, she waits in the nest for one to arrive, and once a male comes, they begin their life together.