They made their debut in the third expansion pack in School of Dragons, Battle for the Edge, and their series debut in Night of the Hunters Part I.
Currently not much is known about them except the Reaper and the Dragon Eye are part of their history.
The Dragon Riders first encountered the Dragon Hunters after Ryker took Stormfly away from Astrid. On their way to their port, Ryker then captured the other dragon riders except Hiccup and Snotlout. Ryker then revealed that he was working with the Berserker Tribe's chief, Dagur the Deranged, his sister Heather, and her dragon Windshear. The riders then found out about the Hunters' dealings, such as making Gronckle Iron, making spear tips with Deadly Nadder spikes, and skinning Zipplebacks for their hides. Luckily, the riders and their dragon were able to escape Ryker's ship with Hiccup's and Snotlout's help.
Ryker and the Dragon Hunters later went to Glacier Island to get a tooth from the Snow Wraith to make their own Dragon Eye key. During this time, Heather and Windshear were actually infiltrating the Dragon Hunters in order to bring them down from the inside. Only Astrid knew of this mission. Ryker and his men failed in capturing the Snow Wraiths.
The Hunters then attacked an island and tortured the wild dragons living there in order to get them to attack Trader Johann and distract Hiccup. They then attacked Dragon's Edge in order to get the Dragon Eye. However, Ryker and Dagur failed when Hiccup returned with the wild dragons.
The Dragon Hunters then breifly captured the Frozen Skrill, but lost it when Hiccup and his riders freed it.
Ryker then brought Dagur, Heather, and his Berserkers to meet with Viggo Grimborn. Viggo and Heather set out to capture a Flightmare. Heather met up with Hiccup and Astrid about the plan and decided to use the opportunity to take the of the Dragon Hunters down. However, Viggo was aware that Heather was a spy and used the riders plan against them, capturing Heather Windshear, and the Flightmare.
Viggo decided to test Hiccup's abilities by leaving the game Maces and Talons on his ship, with pieces representing him, Hiccup, and Heather. Knowing the prize was Heather's life, Hiccup took the challenge. However, Viggo was able to outsmart Hiccup and take the Dragon Eye. Using the Flightmare's mist, Viggo was able to activate the emergency release, giving him access to the Dragon Eye's information, even without a Snow Wraith tooth.
The Dragon Hunter then broke off their alliance with Dagur. They then set up a trap for Hiccup. However, it failed when Dagur helped Hiccup and Toothless escape.
The Dragon Hunters then spread the Scourge of Odin onto one of their ships in order to create a outbreak to demand the only known cure. They were then able to find the last Buffalord on Odin's Respite in order to get the cure from the dragon. However, they were unable to keep the Buffalord caged on their ship.
Ryker and one of his fellow hunters then hosted a series of Dragon Fights that had the Triple Stryke win numerous victories against various dragon. However, it's victories became to routine. However, the hunter in charge of the fights was able to Hiccup and Toothless. Toothless was able to hold his own against a razorwhip and the Triple Sryke. The fights ended when the other riders freed the dragons from the Hunters.
The Dragon Hunters then tried to move a shipment of Dragons and egss, but were stopped by the riders. Using a pair of Quakens, the Dragon Hunters then took large shipments of marble work from island back to their island to build a dragon-proof fortress. However, their efforts were stopped by Hiccup's riders and the fortress was collapsed by the quakens.
The Hunters then set up a trap for the riders, but it failed when Dagur and Shattermaster attacked (and are probably killed).
The Dragon Hunters then had auction which brought in a large number of buyers from across the Barbaric Archipelago. However, the auction ended when the Riders freed the dragons. However, Viggo was able to escape with Berk's gold.
Viggo then decided to make a truce with hiccup on Botany Blight. However, the Hunters used Hiccup's riders to distract Queen Mala and her Defenders of the Wing to take the Eruptodonfrom the Caldera Cay's volcano.