A male wyvern with a red carapace, belonging to the same Rath species as the female Rathian. Appearance and behavior differ between the sexes. While Rathian has dense thorns on her wing joints and tail, a longer chin spike, and focuses on ground-based combat, Rathalos lacks those thorns, has a shorter chin spike, and utilizes more aerial patterns. Furthermore, while Rathian secretes poison through her tail spikes, Rathalos injects venom by scratching prey with the talons on his hind feet. In terms of size, the male Rathalos was traditionally considered larger, but the 15th-anniversary video depicts Rathian as larger. In the 10th-anniversary video, Rathian measures 1653.7cm (1754.37cm in the 15th) and Rathalos measures 1714.7cm (1704.22cm in the 15th). He utilizes the Fire element.

A herbivorous monster in the Monster Hunter series and one of the oldest veterans, appearing alongside the flagship Rathalos since the very first game. It had a perfect attendance record until Monster Hunter World: Iceborne, but missed its streak in Monster Hunter Rise. Its design is based on the real-life herbivorous dinosaur Parasaurolophus. Commonly found in various regions, they always travel in herds and reach sizes of 10m, making them much larger than humans. However, compared to the large monsters of the world, they are on the smaller side. Due to their tasty, nutritious meat and very slow, weak combat ability, they are primary prey for carnivorous monsters. Consequently, the herd flees when attacked by humans or when a large predator appears. Because they are sensitive to danger, a stampeding Aptonoth herd is often a sign that something significant is happening nearby. However, if their young are attacked or in the case of certain males, they may stand their ground and counterattack with their tails or heads. Aptonoth meat is widely traded, and because they are capable of pulling carts, they are kept as livestock in villages. For example, cinematic videos show them pulling wagons, and they can be seen at the return point of the Everwood or behind base camps in the Sunken Hollow and Volcanic Hollow.

As evident from its appearance, its motif is a feathered Tyrannosaurus. According to the developers, it was designed based on the scientific hypothesis that T-Rex might have had feathers. However, the crest that rises from its snout and the pair of hidden sails on its back are distinct from typical theropod dinosaurs. It can use fire breath.

The alpha male of the Jagras, resembling an iguana. The drooping mane growing from its spine is its most striking feature.

A large monster resembling a Tyrannosaurus with massive jaws. It is characterized by a massive body averaging 2046.8cm in length and a physique so muscular it could be described as overdeveloped. Uniquely, it uses Dragon element breath, making it one of the few non-Elder Dragon species capable of wielding Dragon energy.

It possesses a snake-like head with silver-white scales and fur. Like Parnoc and Toridcless, it can build up static electricity by rubbing its fur against the ground.

A Flying Wyvern characterized by its red eyes and black fur covering its body. Its primary habitat is the Great Forest. It served as the flagship monster for Freedom Unite, appearing on the cover and in the opening. Its design is a blend of a bat and a feline, and its name is said to be derived from 'cougar'.

A Flying Wyvern whose appearance is reminiscent of a pinecone. An Elder Dragon-level creature with combat power that few among the Flying Wyverns can match, it is a tyrant of the ecosystem that rivals other Elder Dragon-level threats like Rajang and Deviljho. Like them, it is inherently violent, and its face has a very grim expression reminiscent of a lion. It is also quite large, with its size revealed to be 1928.38cm in the 15th-anniversary size comparison.

It takes a form that seems to combine a dodo with a non-avian theropod and is known to make sounds like a pigeon.

Inhabiting the Ancient Forest, this monster utilizes poison in its attacks. Like Chameleos, it is inspired by a chameleon, but while its colors change based on emotion, it does not cloak itself. It is characterized by an appearance that looks like a chameleon with bat or bird wings; despite its bizarre look—including an extending tongue and poison-spraying tail—it is classified as a Bird Wyvern.