I made this because many people do not know about them. The blue wizards (S. Ithryn Luin) were two wizards sent to contest the will of Sauron in the furthest regions of Middle earth. Tolkien's conception of the two Blue Wizards changed dramatically between his earlier and later writings.
They were only hinted at in The Hobbit and The Lord of the Rings, where Gandalf and Saruman, respectively, say there are five Wizards. However, other writings of Tolkien have more to say. In Tolkien's Of the Rings of Power and the Third Age we are told that aside from Curunír (Saruman), Mithrandir (Gandalf), and Radagast, there were "others of the Istari who went into the east of Middle-earth, and do not come into these tales." Tolkien also writes in Unfinished Tales that the two Wizards were sent to the East. Their names in Valinor were Alatar and Pallando, and they are Maiar of the Vala Oromë. The idea that there were two other wizards in addition to Gandalf, Saruman, and Radagast was first conceived when Saruman in his wrath revealed that there were five members of the Order of Wizards: Later! Yes, when you [Gandalf] also have the Keys of Barad-dûr itself, I suppose; and the crowns of seven kings, and the rods of the Five Wizards. Nothing more was said of these two wizards in The Lord of the Rings as it was published. However, whilst preparing (in 1954) an Index for The Return of the King, Tolkien wrote what his son later referred to as the 'essay on the Istari'. There it is said that of the chief wizards who went to the North of Middle-earth there were five, and two of these were clad in sea-blue. Little was known about these two in the West of Middle-earth; even their individual names were unknown, but they were known collectively as Ithryn Luin, the Blue Wizards. It is said they travelled into the East with Curunír (Saruman) but they did not return into the West. Their fate was unknown, but some held that they fell into evil and became servants of Sauron. Tolkien expanded upon this last point in a letter written in 1958: I really do not know anything clearly about the other two [wizards] – since they do not concern the history of the N[orth].W[est]. I think they went as emissaries to distant regions, East and South, far out of Númenórean range: missionaries to 'enemy-occupied' lands, as it were. What success they had I do not know; but I fear that they failed, as Saruman did, though doubtless in different ways; and I suspect they were founders or beginners of secret cults and 'magic' traditions that outlasted the fall of Sauron. —J.R.R. Tolkien. Tolkien also suggests that only Gandalf returned to Valinor: Wilt thou learn the lore || that was long secret of the Five that came || from a far country? One only returned. || Others never again —J.R.R. Tolkien In a letter, Tolkien says that these two wizards went into the East, and likely failed their mission, perhaps having started magical cults. However, all of this changes in a text written in the last year or two of Tolkien's life. An alternate set of names are given - Morinehtar and Rómestámo (or Rome(n)star), Darkness-slayer and East-helper. It is not clear whether these names were intended to be replacements for Alatar and Pallando or whether they were a second set of names (for instance, their names used in Middle-earth). They are said to have arrived not in the Third Age, but in the Second, around the year SA 1600, the time of the Forging of the One Ring. Their mission though is still to the east, to weaken the forces of Sauron . And it is here said that the Wizards far from failed; rather, they had a pivotal role in the victories of the West at the end of both the Second and the Third Ages. Glorfindel was likely also, Tolkien mentioned later, a shipmate of the Wizards, for he reappears in history about that time. In a brief narrative about a council of the Valar, the origins of the Blue Wizards are placed alongside those of the other three, Curumo (Saruman), Aiwendil (Radagast), and Olórin (Gandalf). Whilst in the essay on the Istari the Blue Wizards are given no names, here they are called Alatar and Pallando. Oromë chose Alatar to send to Middle-earth (to contest the will of Sauron), and Alatar decided to bring along Pallando as his friend. Christopher Tolkien has speculated that their association with Oromë could be because he was the Vala who had the greatest knowledge of the furthest regions of Middle-earth and hence that is where the Blue Wizards journeyed. Based on the above material, the history of the Blue Wizards can be determined as the following: Manwë summons a council of the Valar. They decide to send emissaries to Middle-earth. Oromë chooses to send Alatar, and Alatar brings along his friend Pallando. The Blue Wizards arrive in Middle-earth at roughly the same time as the other wizards c. T.A. 1000 The Blue Wizards travel into the East of Middle-earth with Saruman. Saruman returns to the North West, but the Blue Wizards do not. Together or independent of each other, Alatar and Pallando fall from their appointed task. They may have founded 'magic' cults amongst the peoples of the eastern and southern regions, which existed beyond the downfall of the Lord of the Rings. Towards the end of his life Tolkien returned to the issue of the Blue Wizards. In a brief outline he noted that the Blue Wizards were sent to Middle-earth in the Second Age and were destined to disrupt the work of Sauron in the East: Their task was to circumvent Sauron: to bring help to the few tribes of Men that had rebelled from Melkor-worship, to stir up rebellion ... and after his first fall to search out his hiding (in which they failed) and to cause [?dissension and disarray] among the dark East ... They must have had very great influence on the history of the Second Age and Third Age in weakening and disarraying the forces of East ... who would both in the Second Age and Third Age otherwise have ... outnumbered the West. —J.R.R. Tolkien Therefore Tolkien dramatically altered his conception of the Blue Wizards. They no longer arrived in Middle-earth along with Saruman, Gandalf, and Radagast in c. T.A. 1000. Instead they arrived much earlier, at roughly the same time as Glorfindel in c. S.A. 1600. Whilst Glorfindel was tasked with aiding Elrond with the war in Eriador, the Blue Wizards were destined to journey to the East. Tolkien no longer believed that they drifted from their mission; instead he makes it clear that they played a decisive role in the downfall of Sauron at the end of both the Second Age and the Third Age. They became known as Morinehtar and Rómestámo, Darkness-slayer and East-helper, and were successful in preventing the forces of the East from outnumbering those of the Free peoples in the West. Based on these later writings, a history of the Blue Wizards can be summarised as the following: The two Blue Wizards were sent to Middle-earth at roughly the same time as Glorfindel in c. S.A. 1600 (and similarly at the behest of the Valar), the Year of Dread, when Sauron forged the One Ring and completed the building of Barad-dûr. The Blue Wizards journeyed into the East of Middle-earth, where they remained; they were not heard or seen of west of Mordor. There they became known as Morinehtar and Rómestámo, Darkness-slayer and East-helper. The Blue Wizards were able to hinder Sauron's operations in the East, aiding the defeat of Sauron in the War of the Last Alliance. During the early Third Age and until the end of the Watchful Peace, they were tasked with finding where Sauron dwelt. They failed. Morinehtar and Rómestámo ensured that the forces of the East did not outnumber the West, thus helping secure victory for the Free peoples in War of the Ring. In The Hobbit: An Unexpected Journey, when Bilbo asks Gandalf if there are any other wizards in Middle-earth, Gandalf states there are "five of us": himself, Radagast, Saruman, and the two Blue Wizards, but he has "quite forgotten their names". The exclusion of the Blue wizards' names from that film, according to Peter Jackson in the director's commentary to the extended edition, was due to the film makers' not having acquired rights to the entirety of Tolkien's works, only to The Hobbit and The Lord of the Rings. The wizards' names are never mentioned in the seven books they had rights to, so they were not able to name them in the movies. In the game Middle-Earth: Shadow of Mordor, The Weathered Azurite Figurine, The Two Istari artifact can be found in the north-western part of Sea of Núrnen. In the game are not said their names, but from the description of this artifact we can guess that these two wizards are Alatar and Pallando. In the memory of this artifact is said: "See, there were two of them, and they both came in from the road with a hard look in their eyes, as if they'd traveled too far and seen too much. They were Wizards, true, both of 'em caked in dust, and when one'd talk he'd stop to think and there'd be the other to finish right up, like they had one brain and two mouths. It was creepy for sure, but neither seemed to notice. I heard them say they were hunting the darkness. Damned if I know if they found it. But I guess those fellows can find trouble when they're looking for it. The Sindarin name Ithryn Luin consists of ithryn ("wizards"; plural of ithron) and luin ("blue"). Morinehtar is described as meaning "Darkness-slayer", likely based on the Quenya words mori- ("darkness") and nehtar ("slayer"). Rómestámo (pron. [ˌroːmeˈstaːmo]; or Róme(n)star) is a Quenya name meaning "East-helper".