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A year since Drago’s defeat and no further along with your dragon army I see.
The Warlords are the supporting antagonists in How to Train Your Dragon: The Hidden World. They are a trio of warlords who, after their boss, Drago Bludvist's demise, have hired Grimmel the Grisly to give them Toothless so they can use him to conquer the world.
Chaghatai Khan is voiced by James Sie, Griselda the Grievous is voiced by Julia Emelin and Ragnar the Rock is voiced by Ólafur Darri Ólafsson.
Not much is known about the Warlords other than they have taken over Drago's Army following their leader, Drago Bludvist's defeat one year ago. Having problems with the Berkian Dragon Riders, who mess in all their operations, they hire the renowned dragon hunter Grimmel the Grisly to capture Toothless so they can use the Night Fury to control all other dragons, and conquer the world through it.
The Warlords are first seen discussing with Grimmel about their plans. Later on, they are seen after the Berkians evacuated Berk, having found the island empty and destroyed following Grimmel's attack the previous night, where his Deathgrippers burned the town. Griselda asks Grimmel how Toothless could have escaped once again, and Grimmel reveals that he discovered that the Berkians are heading west. He then explains the Warlords his plan to capture all the dragons, though they don't find amusing Grimmel's twisted sense of humor.
Soon after Grimmel is able to capture both Toothless and the Light Fury, he brings them over to the Warlords. However, he betrays them by revealing that he was never going to let them have Toothless and he was planning to kill him all along, and the Warlords realize they were betrayed by Grimmel. However, the Dragon Riders came to rescue Toothless, and Eret, Valka, and Gobber confront the Warlords. Astrid manages to make two of the ships collide, causing the Warlords to be trapped in a cage. What happens to the Warlords afterwards is unknown, but it can be deduced that any of their men could have released them from the cage and escape aboard one of their ships (if any of their ships survived the ambush), but if not, it's likely that the ship with the cage aboard eventually sunk, dragging the Warlords inside the cage to the depths of the ocean where they would drown.
Chaghatai Khan (current leader & former second-in-command of Drago Bludvist, after Krogan's execution)
Griselda the Grievous (current second-in-command & former third-in-command of Drago Bludvist)
Ragnar the Rock (current third-in-command & former fourth-in-command of Drago Bludvist)
The Warlords are believed to be the secondary antagonists of the film behind Grimmel the Grisly, who represents the main threat to Hiccup and the Berkian Dragon Riders. However, this is untrue, as Grimmel's Deathgrippers served as Grimmel's henchmen and a dangerous threat due to their drugged state whereas the Warlords just had their men to defend themselves.
Ragnar the Rock is a reference to the norse doomsday term, "Ragnarok."