King Runeard

King Runeard is the posthumous main antagonist of Disney's 2019 animated feature film, Frozen II. He was the ruler of Arendelle, and the father of King Agnarr. In his lifetime, Runeard was revered as a noble and generous leader. In truth, he was a ruthless tyrant who believed magic to be a threat to his kingship. In his attempt to eliminate the Northuldra, Runeard sparks a decades-long catastrophe that is then left to his granddaughters, Anna and Elsa, to rectify.

Background
Runeard is the oldest known monarch of Arendelle. His only son and heir was Prince Agnarr. What became of Runeard's wife, Queen Rita, is unknown.

During Runeard‘s reign, the people of Arendelle made peace with the Northuldra, a northern tribe in the Enchanted Forest with a special connection to the elemental spirits of earth, wind, water, and fire. This allegiance was a ploy, however, as Runeard secretly feared the Northuldra due to their association with magic. He declared that they could not be trusted, and orchestrated a plot to eliminate the tribe.

Runeard commissioned the construction of a dam, which was gifted to the Northuldra as a peace offering designed to bring prosperity to their land. In truth, the dam would weaken the Northuldra’s resources and—in their desperation—force them to be susceptible to Runeard. Upon realizing the damage being brought upon by the dam, the leader of the Northuldra consulted Runeard, who offered to heed the leader’s pleas in private. Once alone, Runeard killed the Northuldran leader. This sparked a war between Arendelle and the Northuldra, in during which, Runeard falls off a cliff, to his death. The conflict between Arendelle and the Northuldra angered the spirits, who turned against humanity. In their wrath, the Enchanted Forest was encapsulated within an impenetrable mist that prevented anyone from leaving or entering.

In the decades following Runeard's death, conflicting information spread regarding the origins of the war. The citizens of Arendelle believed that the Northuldra were the enemy, and that Runeard was brutally killed in cold blood. It wouldn't be until Runeard's elder granddaughter, Queen Elsa, traveled to Ahtohallan that the truth behind the late king's motives would be discovered and subsequently shared with the rest of the kingdom.

Frozen II
Runeard first appears during the prologue, when Agnarr recounts the war that cursed the Enchanted Forest. Agnarr recalls watching his father fall to his death, and was unaware that Runeard was the cause of the conflict.

Thirty-four years later, Runeard's granddaughters, Elsa and Anna, journey to the Enchanted Forest after Elsa accidentally awakens the spirits, who then wreak havoc on Arendelle. They encounter the trapped Northuldra and Arendellians who, like Agnarr, are unaware of what truly caused the war that doomed their land. Elsa is eventually driven to seek out the fabled river Ahtohallan for answers. While traversing its caverns, Elsa is able to analyze numerous visions of Arendelle's past, including those involving Runeard. She discovers her his fearful dislike of magic, as well as his plot to control the Northuldra.

With these findings, and nothing but outrage towards her late grandfather for his treacherous actions, Elsa sends a message to Anna in the form of an ice statue, which sculpts Runeard attacking an unarmed Northuldra leader from behind. Deducing that Runeard was the culprit behind the war and also seeing what a heinous scoundrel their grandfather was, Anna realizes that she must destroy the dam to restore peace to Arendelle. By provoking the Earth Giants, Anna is attacked by staggering boulders. She lures the giants to the dam, where their boulders successfully destroy the structure. This causes a massive wave to hurl towards Arendelle, but Elsa is able to block the waters before it could destroy the kingdom. With the dam destroyed, and the truth revealed, peace is restored between Arendelle and the Northuldra, and among the spirits, thus putting an end to Runeard's legacy for good.

Trivia

 * According to Frozen: Forest of Shadows, Runeard oversaw the construction of Arendelle Castle.
 * Elsa’s icy statue depicting the Northuldra leader’s assassination at Runeard‘s hands bears a striking resemblance to the scene in Frozen in which Hans was readying his sword to assassinate Elsa during the climax of the film. The difference, however, is that while Hans failed to kill Elsa, Runeard did succeed in killing the Northuldra leader.
 * Runeard is the first villain to die in the Disney animated feature canon since King Candy in Wreck-It Ralph, seven years prior.