Dragons of How to Train Your Dragon!

Toothless: The only known Night Fury, a rare dragon species.
Stormfly: A tamed Deadly Nadder, characterized by its spiky appearance and agility.
Hookfang: A tamed Monstrous Nightmare, known for its fire-breathing abilities and distinctive appearance.
Meatlug: A tamed Gronkle, recognized for its stocky build and ability to eat rocks.
Barf and Belch: A tamed Hideous Zippleback, notable for its two heads and ability to produce explosive gas.

Night Fury: A rare dragon lineage, exemplified by Toothless, known for speed and stealth.
Deadly Nadder: A common dragon type, like Stormfly, that possesses a spiky tail and strong senses.
Monstrous Nightmare: Another common dragon, represented by Hookfang, known for its fearsome flame.
Gronkle: A common dragon species, similar to Meatlug, often heavyset and good at rock-eating.
Hideous Zippleback: A common species like Barf and Belch, recognized for its dual-headed structure and cleverness.

Stormcutter: Another rare species akin to Cloud Jumper; its unique traits are underlined in the series.
Thunderdrum: Initially Stoick's first dragon, belonging to a common type known for sound waves.
Scauldron: Once common, now considered rare due to its unique abilities.
Sea Shocker: A rare dragon type that exhibits distinct aquatic capabilities.
Whispering Death: Recognized as a common yet intimidating dragon type due to its stealth and effectiveness in hunting.

Skrill: A rare dragon able to control lightning, showcasing powerful elemental skills.
Change Wing: Known for its camouflage abilities, it can change color to adapt to surroundings.
Screaming Death: Rare and massive, it instills fear due to its size and ferocity.

Thornado: Stoick's first dragon, noted for its menacing presence.
Bewilderbeast: Known as the king of dragons, significant in narratives involving Valka and "Race to the Edge."

Sentinels: Statuesque appearances mark this dragon type, creating a sense of eeriness.
Night Terrors: They possess the ability to disguise as other dragons, including Toothless, showcasing their deceptive nature.

Shell Fire: Huge and deadly; its nature remains enigmatic.
Eruptodon: Unique for its consumption of lava, demonstrates adaptability to extreme environments.

Light Fury: A subspecies of the Night Fury, noted for its sleek appearance and agility.
Night Lights: A hybrid of Night Fury and Light Fury, representing a historical first in dragon hybridization.
Sneaky Abomibumble: Hybrid of a Monstrous Nightmare and Gronkle, showcasing traits from both.
Ghastly ZappleJack: A hybrid of TimberJack and Hideous Zippleback, merging features from two distinct dragon classes.
Gorge HushBogle: A combination of Whispering Death and Snow Wraith, indicating a blend of characteristics from both.
Gusty BoltStamper: A hybrid of Skrill and RumbleHorn, illustrating mixed traits from both dragon families.
Bitter GaleSlash: A hybrid between Deadly Nadder and Stormcutter, formerly categorized as part of the Sharp class.

Dragons are divided into distinct categories based on their traits, behavior, and abilities, leading to complex interspecies relationships and interactions.