Mystic Knights of Tir Na Nog is a fantasy-adventure television series set in a fantasy version of ancient Ireland, created by Saban Entertainment. It was loosely based on actual Irish mythology. The name is derived from Tír na nÓg, the Otherworld of Irish mythology. It was Saban's first fantasy series to involve knights, dragons, and wizards. It aired on the Fox Kids Network from September 12, 1998, to May 7, 1999.

The resulting series was an attempt in doing an original non-Japanese special-effects series rather than adapting from actual Japanese tokusatsu.

Ownership of the series passed to Disney in 2001 following Saban Entertainment's closure.

Plot On an unnamed island, queen Maeve of Temra seeks to conquer the peaceful kingdom of Kells and enlists the evil fairy Mider, who gives her the mystical Rune Stone allowing Maeve to use sorcery. Queen Maeve mostly uses the Rune Stone to create or summon monsters whom she sends to wreak havoc. When King Conchobar of Kells seeks a way to protect his kingdom, protagonist Rohan—a druid's apprentice—goes in search of the prophesied hero Draganta, with his friend the reformed thief Angus.

Later joined by the foreign Prince Ivar, and Conchobar's daughter, Princess Deirdre, they are drawn into Tír Na nÓg, whose king Fin Varra puts the group through various tests to determine their worthiness. The heroes having passed these tests, King Fin Varra gives them certain weapons granting control of the classical elements Fire, Air, Water and Earth. Thereafter the four overcome Mider's Evil Sentinels (recurring villains in the series) to capture corresponding suits of armor, and oppose the various monsters created by Maeve, assisted by the winged fairy Aideen. Subsequently, Rohan gains a new partner in Pyre the dragon, who later identifies Rohan as Draganta. Later in the series, another Mystic Knight emerges, in the form of Prince Garrett of Rheged, who joins the others after they free him from Maeve's telepathic control.

With her powers nearly exhausted, queen Maeve summons the monster Lugad, who is more powerful than any previous creation and was trained and mutated by Maeve's teacher Nemain. It was discovered that Lugad and Rohan are both Maeve's abandoned sons. In the series finale, they cooperate with the other Mystic Knights to defeat Maeve, whom King Conchobar banishes to another island. As for Nemain, she has claimed the Silver Chalice that Ivar sought to reclaim as Mider enters an alliance with her.

Characters Mystic Knights Rohan (portrayed by Lochlann Ó Mearáin) – An orphan raised by the druid Cathbad, Rohan is noble, courageous and steadfast. His weapon is the Sword of Kells, which can emit fire. He also has possession of the Dragon's Breath Dagger, which he uses to summon Pyre, the Dragon of Dare. To win his red and gold Mystic Armor, he had to defeat the Ice Lord of Temra. To don his armor, he shouts "Fire within me!". He is also identified as the mighty warrior Draganta, who is destined to bring peace to Kells for 100 lifetimes. Later in the series, Rohan obtains the ability to become more powerful by the war cry, "Battle Fury!" When he has his armor made powerful in the forge within the Mountains of Gloom, his Battle Fury armor is crimson and gold. Eventually it is also revealed that he is the son of Queen Maeve, with Lugad as his half-brother.

Deirdre (portrayed by Lisa Dwan) – The princess of Kells. Her weapon is the Whirlwind Crossbow, which shoots a burst of air. To win her white and gold Mystic Armor, she had to defeat the Lightning Bat of Temra. To don her armor, she speaks the words "Air above me!". Deirdre is the most logical-minded of the Mystic Knights, and is therefore sometimes frustrated by her companions' foibles. Ivar (portrayed by Justin Pierre) – A prince from a distant land, Ivar came to Kells in search of his country's sacred chalice. It was later revealed the chalice was stolen by Torc, Maeve's general. His weapon is the Barbed Trident which shoots blue bolts of electricity. To obtain his blue and gold Armor, he had to defeat the Sea Serpent of Temra. To don his armor, he speaks the words "Water around me!" Ivar is loyal to his friends but can be distracted by his search for the stolen chalice, often to his own detriment. He later gains the Defender vehicle (which was meant to be used for Lugad) from Torc. Angus – (portrayed by Vincent Walsh) - Angus is Rohan's best friend and a well-known, boastful reformed thief who often gets into trouble. His weapon is the Terra Sling Mace which throws giant boulders and can cause earthquakes. To obtain his silver and gold Mystic Armor, he had to defeat the Rock Wolf of Temra. To don his armor, he speaks the words "Earth beneath me!". Garrett (portrayed by Ben Palmer) – Garrett is the prince of Rheged, an ally of Kells. Garrett and Deirdre were promised in marriage and therefore, Garrett first came to Kells to claim his bride. Prior to joining the other knights, he was magically controlled by Maeve, leading him to act against the knights in wicked fashion. However, they eventually freed him with a magic potion and he joined the team. Garrett has a unique ability to command any animal by locking eyes with it, which seems to be independent of his status as a Mystic Knight. His weapons are the Twin Timber Axes which shoot a beam of energy. To obtain his brown and gold Mystic Armor, he had to defeat a giant spider that dwelled in the Banshee Woods. To don his armor, he speaks the words "Forest before me!". In exchange for returning princess Lynette to her homeland, Garrett was given the Dragon Bow Vehicle and he returned with it when the Mystic Knights were facing Lugad. Garrett serves the same role as a "Sixth Ranger" does in many Power Rangers series, supplementing the original team for a time before departing and returning at the climax of their adventures. His storyline is similar to that of Tommy Oliver.

Allies King Conchobar (portrayed by Stephen Brennan) – Conchobar is the king of Kells and the father of Deirdre. With Maeve using dark magic to try to help her win the war between their kingdoms, he is in desperate need of the Mystic Knights' help. Cathbad (portrayed by Barry Cassin) – A druid and advisor to King Conchobar. He also raised Rohan when he was an orphan. A father figure who did his best to raise Rohan as an apprentice. Cathbad is opposed to Rohan's hanging around with Angus because he tends to cause trouble. He can foresee the future and mentors the Mystic Knights. Cathbad's powers can rival Maeve's, but are limited largely to extra-sensory perception. In "Battle of the Druids", it was revealed that his teacher was Seethchenn who had recently allied with Maeve. Cathbad managed to vanquish his teacher in a druid battle. King Fin Varra (portrayed by Peadar Lamb) – The King of Tir Na Nóg. A fairy with great power who gives the Mystic Knights their weapons, as well as occasional advice. He is the rival of the dark fairy Mider. Aideen (portrayed by Kelly Campbell) – A sprite who assists the Mystic Knights. She has affection for Rohan and is consequently jealous of Deirdre. Princess Lynette (portrayed by Aisling Flitton) - The princess of a faraway kingdom. She became shipwrecked due to an attack by a beast called the Grindon which had been pursuing her for quite some time. Grindon came to the island of Kells in search for her and attacked the kingdom's warriors and the Mystic Knights but fled after a lengthy battle. It later attacked the castle, but was repelled by the Mystic Knights. Lynette warned them that it would return at sunset before attempting to leave the castle for their safety, but the Mystic Knights convinced her to stay while devising a plan to lure the Grindon out into the opening. Finally Princess Lynette and Rohan use his sword and slay the Grindon, which she alone could do which as it turned out to be the reason was why Grindon had been pursuing her. After the monster's final defeat, Garrett became her personal escort; with implications of feelings blossoming between them. Pyre: Dragon of Dare – An ancient dragon associated with the Mystic Knight of Fire. At first unwilling to tolerate any human presence, he soon comes to admire Rohan and later recognizes the Knight as Draganta, the legendary hero. Fiercely the rival of Tyrune the Hydra. Pyre wears a gem-studded cuirass, through which he presumably makes contact with the Dragon's Breath Dagger wielded by Rohan. His likeness is worked into the Mystic Knights' armor. To summon Pyre, Rohan would hold out the Dragon's Breath Dagger and quote "Pyre: Dragon of Dare, I summon you".

Villains Queen Maeve (portrayed by Charlotte Bradley) – Maeve is the queen of Temra. She believes that being the ruler of Kells is her birthright, so she recruits the help of the dark fairy Mider. She is later revealed as the mother of both Rohan and Lugad. In the final battle, she takes over Kells until Lugad frees the captive Knights during her fight with Rohan. She uses her magic to assume the form of a naga-like creature with eye beams. Upon being defeated and regressing back to her human form by the combined powers of Rohan and Lugad, Maeve is banished to another island by King Conchobar. As she sees her son for the last time, Rohan himself asks if Maeve has anything to say to him before she is banished. She then replies that he's been trained well and that he's a great warrior except that he's just on the wrong side. Rohan asks her to be taken away. Torc (portrayed by Gerry O'Brien) – Maeve's general who was a former general in Kells before he betrayed them. He stole a silver chalice from Ivar's kingdom, which Maeve needed to enable Mider to travel back and forth between Temra and his realm of dark magic. During the time Lugad was with Maeve, Torc used the Defender vehicle that was meant for Lugad only to lose it to Ivar. In the final battle, he learns that Maeve has been defeated and flees with his army as the Knights have defeated her. As it was mentioned that Torc and his men were last seen fleeing to the woods, Cathbad states that the Temrans are no longer a threat. Mider (portrayed by Ned Dennehy) – A dark fairy who helps Maeve with dark magic. He uses the silver chalice from Ivar's kingdom to transport back and forth between a dark realm to increase his powers. After Maeve's defeat and banishment, he aligned himself with the sorceress Nemain. The Four Sentinels of Temra – These are the four beings that the Knights had to fight in order to gain their Mystic Armor. They later fell under the control of Maeve, having formerly served their creator Mider. The Ice Lord of Temra (portrayed by Shaun Elebert) – A skull-headed ice lord and Queen Maeve's main general. He fights with a curved ice sword. Rohan fought him in order to gain his Mystic Armor. The Lightning Bat of Temra (portrayed by Ned Dennehy) – A bat-headed member of the Four Sentinels. Deirdre fought him in order to gain her Mystic Armor. He wields a bat-shaped boomerang. The Sea Serpent of Temra (portrayed by Enda Kilroy) – A sea serpent-headed member of the Four Sentinels. He uses a weapon called the Serpent-Tongued Whip. Ivar fought him in order to gain his Mystic Armor. The Rock Wolf of Temra (portrayed by Ned Dennehy) – A wolf-headed member of the Four Sentinels. Angus fought him in order to gain his armor. He wields a set of claws on his forearm and a sword. Bogies – Little people who work as spies for Queen Maeve. Tyrune – Tyrune is the three-headed hydra of Temra. Maeve tricked Rohan into saying a druid incantation that released Tyrune from his imprisonment. This giant flying creature sometimes attacks without any warning. Often fights Pyre as they are rival dragons. Tyrune's heads can separate from its body and can attack independently.