Dragon Crests (HTTYD)

The Dragon Crests signify the seven dragon classes and Viking Tribes that use dragons as their mark.

Appearance
The crests take the form of dragons in the Archipelago.

Lore
Each crest has their own history with their tribe and dragons that their based on.
 * Dragon Classes: Seven kinds of dragons serve as the mark(s) of the class of dragons. Stoker (Monstrous Nightmare), Boulder (Gronckle), Fear (Hideous Zippleback), Sharp (Deadly Nadder), Tidal (Scauldron), Mystery (Changewing) and Strike (Night Fury). The marks can be seen in the Book of Dragons and Fear class became Tracker class when How to Train Your Dragon 2 came out. (When the crest would get 'updated' into a different dragon is unknown). Skrills were also said to be the original mark of Strike class dragons before Vikings learned more about Night Furies, A.K.A. Toothless.
 * Hairy Hooligan Tribe: Berk use the Timerjack dragon as their mark and place it on the cover of the Book of Dragons, satchels and chests. For the reason why they use a sharp class dragon is unknown, but it is possible that the Viking that discovered Berk faced one before he could make the island his or her home.
 * Berk Dragon Training Academy: Because the Dragon Training academy was founded by their leader Hiccup and his dragon, Toothless, was the very first dragon to ever be trained, the Dragon Academy's crest is that of the Strike Class symbol (the Night Fury), but with a red-colored tailfin to emulate Toothless' prosthetic.
 * Berserker Tribe: Dagur's tribe use a Skrill (a Strike class dragon) as their mark. The tribe was said to have enslaved Skrills by using them as live lightning shooting weapons, when or who stopped it is unknown.
 * Drago Bludvist: Drago's armada have more than one kind of dragon(s) on their sailors, most of them look like Monstrous Nightmares and dragons with weapons.
 * Dragon Eye: The Dragon Eye is covered in dragon crests and markings, like old fashioned dragon class marks around the jewel that dragon's shine their flames into. On the cylinder and in it's projections from the 'dragon' lenses.

Some tribes, like the Outcasts and Dragon Trappers don't use dragons as their mark and some Vikings like to place different kinds of dragon marks on objects like Shields, Flags, Totem poles (mostly in School of Dragons), Sails, Belts, (on or in) Books and more. They can even be placed on buildings and be their mark, like the Berk Dragon Training Academy with the one red tailfin Night Fury.

Role in the Crossover
While that are the crests of tribes and dragon classes, fans see the Strike Class mark (or the Viking/Helmet crest on Toothless' red tailfin) as Hiccup's RotBTD crest, much like how Corona's sun crest is associated with Rapunzel Corona and DunBroch's crest is Merida DunBroch's.