Middle-earth has many powers at work, most of them defying comprehension. Among the more intriguing are the Maiar. These beings are pivotal to events not just in The Lord of the Rings, but in all of the fantasy world's history. What's sad is that their influence likely goes unnoticed by anyone only watching the films.
In reality, J.R.R. Tolkien chronicled numerous Maiar exploits in his books, notably The Silmarillion. Followers of those works have a unique perspective on these mysterious beings. This, in turn, changes the way they experience the mainline Lord of the Rings story. As such, their importance can't be overstated.
7 They're Essentially Angels
The Maiar are vague beings who serve the Valar. These are basically the gods of Middle-earth and all of Arda. Along with their own master, Eru Ilúvatar, they created the world and fashioned a grand plan for its existence.
They then formed the Maiar to safeguard that world. Aiding the divine design is their key duty. This mostly comes down to maintaining peace and keeping any darkness at bay. It's a job they carry out tirelessly, as sinister forces always try to worm their way back to power.
6 They Can Shapeshift
As the kin of the Valar, looking directly at the Maiar would likely overwhelm an unassuming resident of Middle-earth. Thankfully, these spirits can change their form. Not only can they pass as Elves or other earthly beings, but they can disappear entirely.
The Maiar used these abilities to appear trustworthy to the Elves of the First Age. Adopting fair forms was instrumental in convincing these early residents to migrate from Middle-earth to Valinor. The Valar decreed this to help them escape impending danger, specifically from one of their own.
5 They Were Corrupted By Morgoth
Even angels can fall, especially when confronted by the Middle-earth equivalent of the Devil. Melkor was originally one of the Valar. His hunger for power led him to betray his kin, ultimately desecrating their lands with his theft of the Silmarills and earning the new name, "Morgoth." On top of being a formidable foe on his own, he proved extremely skilled at manipulation and mutilation.
He used these gifts to turn many Maiar to his side. Those under his thrall took numerous terrifying shapes, with the most prominent being the demonic balrogs. That would explain their winged and horned appearance. As terrible as these creatures were, however, Morgoth's treachery also yielded something worse...
4 Sauron Is One Of Them
Chief among Morgoth's servants was Sauron. He's a Maia himself and came with many abilities unique to them. He made particular use of shapeshifting to turn into wolves and vampires. However, he could also take on a fair form. Not only did this aid in his manipulation, but it spoke to what distinguished him from Morgoth's other thralls.
Because his master valued him so much, Sauron had more agency than the Dark Lord's other servants. Suffice it to say, a brainless balrog would have a hard time bending anyone to its will. Unfortunately, Sauron lost much of his deceptive power along with his fair form after causing Númenor's destruction. This didn't make him any easier to kill, however, as evidenced by The Lord of the Rings. Sauron was perhaps the only Maiar with power comparable to the Valar.
3 One Married An Elf
Among the most enchanted Maia was Melian. This maiden roamed the forests of Middle-earth, bringing joy to its residents through her singing. One such resident was an Elf named Thingol. They met during his people's mass exodus to Valinor. However, he never made it to that land.
Rather, they both stayed in Middle-earth and began the kingdom of Doriath. They not only provided a place of sanctuary for thousands of years but later gave birth to Lúthien. She later became known for her own mystical beauty and romantic adventures with Beren. This makes Melian a direct ancestor of iconic Lord of the Rings characters like Elrond and, by extension, Arwen.
2 They Formed The Five Wizards
The Maiar also manifested in the Third Age, taking the form of Wizards. They were Saruman the White, Gandalf the Grey, Radagast the Brown, and two Blue Wizards: Alatar and Pallando. Same as before, their goal was to safeguard the world from dark forces. Mostly, their tasks came down to thwarting Sauron and his ilk. Though Saruman was originally the most powerful of the group, the pecking order was not absolute, especially once he himself succumbed to corruption.
In The Two Towers, Gandalf returned from death as the new White Wizard. The details surrounding this remain sketchy. He claimed to have been sent back until his task was done. This led many to theorize he was resurrected as part of a grand plan by the Valar king, Manwë, or the original creator, Eru Ilúvatar. Either way, this phenomenon showed that the Valar still love those who faithfully serve them.
1 They Carry The Sun And Moon
Part of forming the planet involved creating a cycle. This originally fell to the Two Trees of Valinor. Their rotating cycles of divine light established day and night. Sadly, Morgoth enlisted Ungoliant the spider to poison these trees and plunge the world into darkness. Since neither the Valar nor the resident Elves could replicate the holy energy, the task of bringing light back to Arda fell to the Maiar.
Two of them carried the last remnants of the trees around the world, thus emulating the cycle. Arien, a powerful fire spirit, steered the vessel of the Sun. Talion, a hunter spirit, acted as the Moon. This is why Tolkien refers to these celestial bodies by gender. Moreover, it speaks to the Maiar's ingenuity, their unending devotion, and their enduring impact on the world.