Sentinel

"The Sentinels run this place with an iron fist. They eat nothing but that fruit. They've never encountered Night Furies before, and that would be about the only dragon they haven't seen. And, speaking of seeing, they don't. But they seem to track pretty well for something that's blind."

- Hiccup

The Sentinel is a large Boulder Class dragon that first appeared in Dragons: Race to the Edge.

Official Description
"Although sightless, the Sentinels still keep close watch over the dragon graveyard on the Isle of Vanaheim. Often mistaken for stone statues, the Sentinels remain absolutely still when they allow ailing dragons to enter Vanaheim. But at first hint of an intruder, these sentries defend the sacred burial ground with sonic screeches and downdraft wingblasts. Born blind, sentinels have evolved their senses of hearing and smell to hyper-keen levels, making them incredibly alert. Yet despite their fearsome appearance, Sentinels show a a softer side by caring for the old and ill dragons who have come to spend their final days on Vanaheim. If you're unsure how to handle an unfamiliar type of dragon, just follow a Sentinel's lead. These observant dragons have kept vigil over every class and every breed to pass into their cemetery, making them the dragon experts of the dragon world."

- Dragonpedia

"Although sightless, the Sentinels still keep close watch over the dragon Graveyard on the Isle of Vanaheim. These vast, stony Dragons show little room for weakness, but a clever mind can exploit their blindness. Be wary, however; they have a keen sense of smell."

- Dragons: Rise of Berk

"The Sentinels spend their lives perched on the sea stacks all through the outskirts of Vanaheim, where they watch over the dragons who have made this island their final resting place. They ensure that only those in need are able to pass through to Vanaheim. If the Sentinels find a dragon or Viking intruding, they will do all that they can to protect the island and its inhabitants. The sonic screech is used by the Sentinel to disorient their opponents. The Sentinel also uses its strong and powerful wings to defend the island by creating downdraft wingblasts. This move is strong enough to take out threats straight from both the sky and the ocean. Compared to other dragons, the Sentinel’s firepower is considered to be elite. In addition to its impressive collection of defensive moves, the Sentinel is also known for having enhanced senses as a result of its inability to see. While Sentinels may be blind, this dragon is still able to move around and maneuver itself with relative ease. This is a result of having overly developed senses, especially its sense of smell. This ability has allowed the Sentinel to be able to recognize friend or foe from their scent alone. The Sentinel’s advanced senses and impressive skills combined with its speed and agility make it quite a powerful dragon."

- School of Dragons Website

Egg
A Sentinel egg is round shaped and is covered in what appears to be rocky plate. The pattern and color are reminiscent of an adult's back scales.

Hatchling to Adult
Sentinels are large dragons iconic for their tough rock-like epidermal layers that if pieced together with smaller stones, make them almost seemingly covered in moss. Their stature and bony wings resemble that of gargoyles. These scale clusters are more prominent on their faces and form rows of bony plates on their chest. They have a pair of short horns on their head, complemented by similar ones on along their neck and one on their nose. These dragons are blind and thus have a translucent blue cataract over their eyes.

Titan Wing
Titan Wing Sentinels are almost identical to adults. However, instead of a stony gray, they are grey blue with black patterns. Their eyes are bright yellow.

Sonic Screeches
The Sentinels defend Vanaheim with their sonic screeches that can disorientate several dragons. These screeches are powerful enough to put off the fire jacket of a Monstrous Nightmare and knock it out of the sky.

Firepower
The Sentinels can breathe normal streams of fire, capable of igniting Zippleback gas from a considerable distance.

Downdraft Wingblasts
In order to chase dragons back to Vanaheim or keep them away from the island, the Sentinels often use their powerful wings to create a downdraft wingblast. These blasts are strong enough to knock dragons out off the air and slow down falling dragons enough to not die or break bones when they hit the ground.

Remaining Motionless
The Sentinels are capable of remaining motionless for days at a time, which allows them to surprise and ambush unsuspecting adversaries or intruders in Vanaheim.

Teamwork
These dragons are known to work in teams. When stationary, they each have different posts and positions to take up around the island. Upon the threat of dragons leaving, they often corner them in the air in small groups.

Heightened Senses
Born blind, Sentinels have developed extremely sharp hearing and smell to navigate and track other dragons. They also possess the ability to remember scents after a long period of time and adapt accordingly.

Dragon Knowledge
Sentinels are extremely knowledgeable about the different dragon classes and breeds because numerous dying dragons go to Vanaheim. As such, they are said to know the strengths and weaknesses of nearly all known dragon species, except for a few, like the Night Fury. They use these to help care for and cater to the needs of different dragons, along with helping construct their funeral grounds.

Hibernating
As shown in "Guardians of Vanaheim", the Sentinels hibernate when they are injured or sick, in order to heal. The hibernation is a slow process and the only way to speed the process quickly is if the Sentinels are exposed to great amounts of heat.

Strength and Combat
Having a tough skin, Sentinels are able to resist powerful attacks, such as Night Fury blasts, as seen in "A Matter of Perspective". They show no signs of injuries when they are hit by Grim Gnasher teeth or Deadly Nadder spikes, which are really sharp and launched at great speed.

Blindness
As aforementioned, Sentinels are born blind. Despite having sharp hearing and smell, they can be outsmarted by several dragons that cover up their scent with Vanaheim Fruit and move silently.

Unknown Dragons
Dragons that the Sentinels don’t know too well like the Night Fury and any other dragon that never rested on the island can easily avoid them, as proven by Toothless.

Pepper Gas
According to School of Dragons, chemical attacks such as Pepper gas can confound a Sentinel's acute sense of smell, as well as burn their mouths and eyes, effectively incapacitating them.

Behavior and Personality
Sentinels are born solely to guard the funeral grounds of Vanaheim and assist sick or dying dragons there. As such, they rule the area with an iron fist as they forbid any dragons from leaving the area. They are also extremely aggressive to the Grim Gnashers, which are perfectly healthy and prey on sick dragons.

They guard the area on various posts around and on the island, perpetually stiff and stationary like statues. However, upon the slightest sign of threat, they crackle awake.

However, they do exhibit kindness and fondness to the inhabitants of Vanaheim. They help to construct funeral grounds and provide them with food. The former action makes Fishlegs believe that these dragons are capable of abstract thinking and knowledge of life and death.

In the game, School of Dragons, the Sentinels are mentioned as being pack-type dragons with a lead dragon which directs the activities of the other Sentinels. The Elder Sentinel is distinguished from other Sentinels by additional bony horns or growths on its head and increased stamina.

Training
By showcasing the right intentions, Sentinels appear to be less hostile. By helping them guard the area and proving that you are of no threat, Sentinels will grant you the respect and lower their aggression, even allowing you in and out of the island.

At the release of the "Wrath of Stormheart" expansion in School of Dragons, Sentinels can be trained from the egg or by bonding with an adult.

Season 5
Sentinels made their debut in the episode, "A Matter of Perspective" when the Dragon Riders go to Vanaheim. They also appear in the episode, "Searching for Oswald... and Chicken".

Season 6
The Sentinels return in the episode, "Guardians of Vanaheim", in which they are hibernating from their injuries.

How to Train Your Dragon The Hidden World The Movie Storybook
A Sentinel was briefly seen being ridden by an unnamed Viking in this book, following the Alpha Dragon Toothless on a quest for the Hidden World.

Dragons: Rise of Berk
The Sentinel was introduced in this game along with its Titan Wing form and a premium individual, Silent Knight. Later, other individual Sentinels were released: Cinder and Mossguard.

School of Dragons
Sentinels were introduced to the game in March 2018 at the release of the "Wrath of Stormheart" Expansion. Several NPC (non-playable characters) sentinels appear on Vanaheim and at one point are infected by Grimora. The Elder Sentinel also appears and accompanies the player around the Archipelago assisting in battles. Ultimately it is trained by the player.

Non-elder Sentinels are also available to purchase as eggs at the Trading Post.

Regular Sentinel

Elder Sentinel

Trivia

 * The Sentinel shares statue-like similarities to the Victorian-era gargoyles.
 * Even though the Sentinels are blind, they have small pupils.
 * The word "sentinel" means "guardian", which is the role that the species play for Vanaheim.
 * The Sentinels’ protective behavior towards Vanaheim is possibly inspired by that of the Dragon Guardians of Tomorrow from the Book series.
 * According to Fishlegs, the Sentinels don't have a tomb for their final resting place.