Essetir is a kingdom in Albion that lies near Camelot and is currently ruled by King Lot. It was previously ruled by King Cenred, and during this time the kingdom battled with Camelot twice. The first was won by Camelot, the second by Essetir. Essetir won one battle because they were in possession of an immortal army. It was during this battle that Cenred was killed by Morgause because she wanted full control over his army.
The brigand Kanen and his army terrorized the country and particularly the village of Ealdor. The people of Ealdor came to Cenred for help, but he refused to take action. Soon, Merlin, Guinevere, Morgana, and Arthur arrived and taught the villagers to stand up and fight against Kanen. When Kanen returned with more brigands and launched the Battle of Ealdor, the villagers were able to fight back and Kanen was killed by Arthur at the end of the battle (The Moment of Truth).
When the dragon attacked Camelot, Arthur and Merlin went in search of the last Dragonlord, Balinor, who was also Merlin's father. They succeeded, discovering Balinor living in a cave in the kingdom of Essetir, but Balinor was killed before he reached Camelot. Merlin inherited his father's powers, therefore becoming the last Dragonlord himself which allowed him to control Kilgharrah and end his attack on Camelot (The Last Dragonlord). According to Arthur, Cenred's army was vastly inferior to the Knights of Camelot due to Cenred relying heavily on mercenaries. Camelot succeeded in defeating Cenred's army even while being outnumbered two to one.
Morgana used a mandrake root to cause Uther to experience hallucinations that made him appear to be going mad, leaving many doubting his ability to lead Camelot. Morgause told Cenred that Uther was weak and without a leader Camelot was vulnerable. Cenred, however, was unsure, stating that even with Uther incapacitated, an assault on Camelot could not be taken lightly. Morgause informed him that she had an ally in the court; Cenred doubted that the ally, Morgana, was reliable, due to her betraying Camelot, her former home.
Morgause assured him that Morgana could be counted on until the end, convincing Cenred to participate in the fight for Camelot. He then gathered his forces, with mercenaries flooding into his kingdom. Camelot scouts witnessed this and rushed to inform Uther. The invasion force was soon complete and he led his soldiers to the weakened kingdom of Camelot in their thousands.
Gaius suggested they negotiate with Cenred, if only to buy them time to prepare, but Arthur, knowing Cenred would not be easily satisfied, ordered Camelot to prepare for a siege, insisting that the castle had never been taken, thereby giving them the advantage. He also ordered that the people of Camelot's outlying villages took shelter within the city. When Leon argued they'd be leaving behind their homes and livestock which Cenred would certainly destroy, Arthur said they'd still have their lives. With Cenred's army only hours away, preparations began in full; weapons and armour were distributed, barricades and defences were erected and the knights of Camelot prepared for battle.
As night fell, Cenred's army surrounded the city. At the urging of Morgause, Cenred began the attack; as catapults bombarded Camelot, Cenred's army broke through the city gates and battle erupted in the streets. Arthur and his men defended the walls and barricades, holding Cenred's men from advancing, and Uther, ignoring the advice of Gaius, Leon and Arthur, donned armour and joined the battle, fighting against the invaders. Arthur pulled him back but he refused to let his kingdom fall, but was hit in the leg with a crossbow bolt. With their king injured and Cenred's men overrunning the barricades, Arthur ordered a retreat back to the castle.
As Cenred's men advanced on them, Merlin used magic to block their path with fire, leaving the lower town to the attackers. Cenred stated that taking the castle would be much more difficult, but Morgause assured him that Morgana would fulfill her side of their bargain. Meanwhile, in the castle, Morgana went down to the crypts with the hawthorn staff. She drove the staff into the stone floor, awaking the dead of Camelot and forming an undead skeleton army. As the Knights of Camelot fought a desperate battle to keep Cenred's men from breaking into the castle, they were shocked to find skeleton warriors begin to emerge from the castle and attack them from behind. As Arthur and his men fought a battle on two fronts to hold off Cenred's men and the undead, Merlin headed down to the crypt and duelled with Morgana, until Merlin used his magic to cause part of the ceiling to collapse, knocking her out.
With Morgana incapacitated, Merlin used his magic and his sword to shatter the staff. When the necromantic enchantment animating them broke, the skeleton warriors collapsed into inert piles of bones. With the undead threat defeated, the knights of Camelot returned to the battle against Cenred's men, fighting with renewed vigour. Seeing the battle turning against him, Cenred ordered his army to retreat, ignoring a furious Morgause's warning that he had failed her (The Tears of Uther Pendragon).
Cenred then kidnapped Elyan and later Guinevere, so she could lure Arthur to him. Guinevere warned Arthur of Cenred's plan, but despite this, Arthur decided he, Gwen, Merlin and Morgana would go to save Elyan. They succeeded, and Merlin defeated Morgause and Cenred (The Castle of Fyrien).
A Camelot patrol led by Sir Leon accidentally trespassed in the kingdom and all, except Leon, were slaughtered. Leon was found and rescued from near death by a group of Druids who made him drink from the Cup of Life. When Morgana heard Leon inform Uther of this, Cenred and Morgause decided to claim it for themselves so Camelot would be at their mercy.
When Arthur, Merlin, and Gwaine escaped from Jarl's clutches, Jarl came to Morgause and Cenred with important information, revealing that the man he captured was the Prince of Camelot. A group of Cenred's knights were then sent to claim the cup from the trio, which they did. Morgause then used it to turn Cenred's forces into an immortal army, and by doing so, his men were under her control. She then betrayed Cenred, and because she had no further use for him, had him killed. The immortal army was then used to conquer Camelot and put Morgana on the throne as Queen (The Coming of Arthur).
- Essetir is the only kingdom outside Camelot that has appeared in every series.
- Essetir appeared in the episode "Aithusa"- the knights and Merlin travelled through Essetir to get to the Tomb of Ashkanar. This is known because, in a deleted scene, Merlin told Arthur that this was the place where his father died, and Balinor died in Essetir in the episode "The Last Dragonlord". To support this, some of the filming of "Aithusa" was in the same area as of some of the filming of "The Last Dragonlord".
- Essetir can be spelled several ways. Variations include Escetir and Ascetir.