Protoss

The Protoss are the first "creation" of the Xel'Naga (also calling themselves "The First Born", considering the Zerg was the second creation of the Xel'Naga), which unintentionally led to the creation of the Zerg. They meant to give the Protoss "Purity of Form".

Biology
The Protoss are approximately 3 meters tall, and are bipedal, standing upon two, two-digit digitigrade legs while manipulating objects with two, four digit hands—two of which are opposable. Their chests and shoulders are broad, while their waists narrow significantly; the midsections are slim. The hands are in fact clawed, and can be used as deadly weapons should the Protoss be cornered unarmed.

Their skin is a scaled, semi-permeable surface, through which they will absorb what little water they require to survive. It is capable of changing colors, likely through chromatophores, which occurs to display their emotions visually. However, the skin is capable of both hearing and smelling; their olfactory sense is sharp enough to properly identify other Protoss. That being said, their primary sense appears to be sight. Their eyes are two glowing spheres embedded in their heads, and are capable of seeing very well, even at night.

The head ends in a bony crest, extending from the crown. Beneath this emerges the nerve cords, which grant them access to their racial psionic gestalt—it is this gestalt that is the basis to the Khala. Mentally, the Protoss sleep and dream in manners similar to Humans.

They are totally bereft of mouths, noses, and ears, as they need none of these to survive. While the reasoning for their lack of noses and ears are explained above, they lack mouths because of the photosynthetic abilities of their skin, making the Protoss autotrophs. They are advanced enough to be able to survive off of moonlight as opposed to sunlight, and can go for extended periods of time without being under the sun. However, the Dark Templar were seen to survive on the formerly dark world of Shakuras; how they accomplished this is unknown, but may be related to some biological modifications they made to themselves. Another viable possibility is that they are actually capable of using any form of cosmic radiation as 'sustenance'.

Since they do not need to eat like many other creatures would have to, they would not eat the creatures they hunted, instead only hunting them to collect their blood and the hides, used for a variety of purposes in their culture. They no longer seem to hunt, however, likely creating synthetic properties to use in the stead of any blood or hides originally required.

They are an incredibly adaptable and resilient species, able to survive in harsh natural conditions and climates. This, coupled with their strength and speed which were considered unparalleled by the Xel'Naga, led to the latter seeing the former as having purity of form, leading them to manipulate the species as they saw fit.

While their bodies are sustained using blue or purple, slightly iridescent blood, they also possess a psionic pulse that is encased within their physical shell, which may serve the purpose of a soul. Once their body is destroyed and they subsequently perish, this psionic pulse will dissipate, resulting in a flare of pale blue light that vaporizes any remains. With training, they can phase quietly into the Khala.

The average life expectancy of a Protoss is at least a thousand years, as seen in Matriarch Raszagal. Protoss under 300 years of age will rarely hold any form of significant political position. Artanis, who is 262 years old, is considered young, despite his powerful military position.

Philosophy
Protoss religion came about thanks to the wars that plagued their kind upon Aiur following the abandonment from the Xel'Naga. Finally united under the teachings of Khas after many generations of all-out warfare, the Protoss people began to adhere to the teachings of Khas, which was deemed "Khala", or the "Path of Ascension". Khala stated that if a Protoss warrior were to die in battle, then they would reach "Khala's End". Below are two philosophies of the Protoss:
 * Khala ("Path of Ascension"): This personal philosophy emphasizes inner peace and communal brotherhood. It also reflects in the caste system of the Protoss, where all castes are considered different but equal and working towards the same goal.
 * Dae'Uhl ("Great Stewardship"): This official policy was developed to concern the encountering of other races. Dae'Uhl is a strict code that, above all, protects life on the whole, while simultaneously mandating an inarguable policy of non-interference with the races they watch over, similar too the Prime Directive.

Aeon of Strife
The Aeon of Strife began when the Xel'Naga "abandoned" the Protoss, because they had forgotten their psionic gestalt field, which was what had drawn them in the first place. Each tribe blamed every other tribe, and the Protoss disintegrated into warring, primitive savages. This lasted until a mystic, name Savassan, who gained the title "Khas" (He who Brings Order), found a stockpile of Khaydarin Crystals, left behind by the Xel'Naga. After studying the crystals, he and his assistant, Temlaa, entered their psionic gestalt, the Khala. He gathered the tribal leaders, and instructed them on how to enter the Khala.

Golden Age
After the Aeon of Strife, Savassan's name was forgotten. The Protoss technology level shot upwards. They began to expand, defeating all who stood against them. They created the Motherships, huge saucer-shaped vehicles, with enough space for an entire colony, and enough power to rip holes in the fabric of space-time. It was "a good time to be alive".

The Dark Templar
However, as with all good times, it had to end. The Conclave, the Protoss government caste found out about a small group of Protoss who did not embrace the Khala. They demanded their greatest hero, Adun, to murder all these dissidents. However, Adun refused, instead teaching the Nerazim, or "Dark Templar", to become invisible. A small group of Dark Templar began experimenting with something - nobody knows what - and caused a devastating storm over Aiur. The conclave was furious with Adun for disobeying them, and decided to banish them, forbidding Adun to see them off. Again, Adun disobeyed. The Conclave, again furious, began attacking the refugees. Sacrificing himself, Adun was able to use both Light and Dark energy to protect them long enough to escape.

Coming of the Zerg
The Protoss began expanding again, pushing ever outwards, meeting and greeting several alien races, including Humanity. After several centuries, they discovered a few small organisms, which they captured for study. One of the tests they used was how they responded to Khaydarin crystals; the beings handled the energy just fine. They then read the minds of the probes, and were dismayed to find that they were the harbingers of a new terror, the Zerg.

The Zerg attacked a Human colony world, Chau Sara, and the Protoss had no choice but to destroy the planet through a process called Sterilization or Purification. A fleet of 50 protoss warships warped into range and burned the entire planet's surface from space. Blasting away the atmosphere, vaporizing the seas, and liquefying the entire crust down to the upper mantle, no living organism, zerg, human, or indigenous lifeform, survived the extermination. Several more terran worlds were cleansed with this process. However, the Protoss commander, Tassadar, found murdering humans abhorrent, and often committed to long planetary campaigns to give the humans time to escape, disobeying the Conclave like Adun before him.

Alongside this, a small group of Dark Templar, led by their Prelate Zeratul, found that Void Psionics could permanently kill Zerg Cerebrates. They landed on Char, a planet housing the main bulk of Zerg forces, and tested their theory on a Cerebrate named Zasz. It proved a successful venture, but with a terrible price. Zeratul's mind brushed the Overmind's, unintentionally telling him the location of Aiur. The Zerg quickly attacked it, bringing shame on Tassadar and the entire Templar Caste.

Invasion of Aiur
The Zerg stole Khaydarin Crystals and established themselves on Aiur, manifesting the Overmind within a Xel'naga temple and slaying the hero Fenix in the Temple of Antioch. Sometime during this struggle, the Shrine used for integrating badly injured Templar into Dragoon walkers was destroyed or taken over by the Zerg. In order to defeat the Overmind and its Cerebrates, Tassadar convinced Zeratul and his fellow Dark Templar, along with a group of Humans led by James Raynor, to return with him to Aiur. The Conclave, enraged by the return of those who refused the Khala, declared Tassadar and all who followed him to be traitors and sought to execute him for treason. Although Tassadar chose to surrender rather than watch the Protoss kill one another, his allies freed him and continued the war effort against the Zerg. After Tassadar's forces killed another Cerebrate, the Conclave realised their mistake and pledged their support to him in fighting the Overmind. After an intense battle with the Overmind, Tassadar used both Khala and Void psionics to permanently kill the creature, sacrificing himself in the process and rendering the rest of the Zerg feral.

Flight to Shakuras
Despite their victory against the Overmind, Aiur remained in ruins, infested with mindless Zerg. With their civilisation destroyed, the remainder of the Khalai Protoss jumped through a Warp Gate to Shakuras, the adopted homeworld of the Dark Templar.

Unfortunately, a small brood of Zerg made it to Shakuras first, although the Protoss quickly dispatched them. However, Shakuras, like Aiur, soon became infested by the Zerg. During this time, the Protoss were visited by Sarah Kerrigan, a Human-Zerg hybrid created by the Overmind to serve as its deadliest agent. Her mind freed after the Overmind's death, Kerrigan revealed to the Protoss that a civil war had broken out among the Zerg and that the remaining Cerebrates were in the process of creating a new Overmind. With Kerrigan's aid, The Protoss went on a quest to obtain two gems, the Uraj and the Khalis, with which they would purge the Zerg from Shakuras. However, upon their return to Shakuras, they discovered that Judicator Aldaris, the last surviving member of the Conclave, had incited a violent Khalai uprising against the Nerazim. Raszagal, matriarch of the Dark Templar, expressed her belief that the rebels were driven by their old prejudice against her people, and so ordered the execution of the traitorous Judicator. Despite the efforts of Artanis and Zeratul to apprehend him, Aldaris is killed by Kerrigan as he attempts to reveal a "dark secret" he discovered about Razsagal. Zeratul, enraged by Kerrigan's actions, banished her from Shakuras. With the rebellion quelled, the Protoss brought the Uraj and Khalis crystals to the local Xel'naga temple, the former imbued with a massive amount of Kala energy and the latter comprised of Void energy. Within the Xel'Naga temple, the energies of the crystals were focused, intertwined, and channelled into a massive explosion that scoured the Zerg from Shakuras.

The Brood War
During the time that the Protoss were fighting to keep Shakuras from Zerg control, other survivors remaining on Aiur were recovered by Kerrigan, along with their Human allies. Kerrigan revealed to Raynor and Fenix the existence of the new Overmind and the efforts of the United Earth Directorate to enslave it. An unlikely alliance was established between them as Fenix led the Protoss against the UED and their Zerg slave broods. However, shortly after driving the UED from Korhal, Kerrigan betrayed and slaughtered her allies, including Fenix. A few days later, Kerrigan returned to Shakuras and abducted Matriarch Razsagal, using her as bait to lure the Dark Templar back to Char. Leading the contingent sent to recover their Matriarch, Zeratul confronted Kerrigan, who offered to return Razsagal on the condition that he first kills the new Overmind. Upon his success, Kerrigan revealed to Zeratul that she had enthralled Razsagal's mind, making her a mindless puppet of the Queen of Blades (it is implied that Kerrigan had been controlling Razsagal for some time, and that Judicator Aldaris discovered this, hence his rebellion). Intitially, the Protoss attempted to recover Razsagal in the hopes of restoring her mind but were thwarted by the Zerg. Rather than leave his Matriarch in her current state, Zeratul elected to kill her, briefly freeing her mind in her last moments. Kerrigan, surprised by Zeratul's actions, decided to spare his life and allowed him to leave, if only to suffer in shame. A short time later, Artanis arrived at Char with a considerable Protoss fleet intent on retaliation against the Queen of Blades. Coincidentally, Human fleets from the UED and Terran Dominion had also arrived at the same time with the same intent. Despite their combined efforts, the Zerg overpowered the three factions and drove them back.

Aftermath
The Protoss have recovered since the Brood War, bringing home their Motherships and retrieving the massive Colossus war-robots. They have also experimented with combining Void and Khala psionics, resulting in the creation of the Warp Ray and Twilight Archon. Despite enduring racial tensions, the Khalai and Neraziim Protoss fully united under a new civilisation, the Protoss Daelaam. Artanis is made Hierarch of the Daelaam and Vorazun, Razsagal's daughter, assumes the role of Dark Templar Matriarch. Meanwhile, Zeratul discovered a clandestine research facility, where Humans were conducting experiments on Protoss and Zerg and even splicing their genetics, creating monstrous hybrids of the two species. Zeratul also discovered the mastermind behind these experiments, Lieutenant Samir Duran, a Human soldier of the Terran Confederacy who defected to the UED, then betrayed them to Kerrigan after seemingly becoming infested. During their confrontation, Duran revealed to Zeratul that he was neither Human nor Infested, but a disguised Xel'naga, one who had been manipulating the conflict between the Protoss, Zerg and Humans in order to create a Hybrid army for his master. Zeratul since sought out whatever knowledge he could find about this.

Wings of Liberty
Protoss forces followed Zeratul to the planet Ulaan, where he learned of a prophecy about the return of the Xel'naga and the imminent apocalypse. Although the Protoss were massacred by the Zerg, Zeratul escaped and bought the prophecy to the planet Zhakul in the hopes of having it interpreted by the Protoss Preservers. However, he discovered the Preservers had been imprisoned and their protective forces corrupted by Maar, a Protoss-Zerg Hybrid. Zeratul and his forces eventually destroyed Maar and freed the Preservers, who examined the prophecy and discovered an apparent reference to the Zerg Overmind. Following this new lead, Zeratul returned to Aiur to commune with the remains of the Overmind. At this point, he was contacted by a Xel'naga known as Ouros, under the guise of Tassadar speaking from beyond death. He reveals the truth to Zeratul, that the Zerg were created by a fallen Xel'naga known as Amon in a bid to destroy all that the Xel'naga had created, that the Overmind was merely a slave to Amon and that it created the Queen of Blades in a bid to free the Zerg from Amon's control. As Ouros conveyed this information, he showed Zeratul a vision of the future that the Overmind had also witnessed, a future in which Amon and his Hybrids exerminated all life in the universe, including the Protoss, Humans and Zerg. Horrified by this vision, Zeratul proceeded to record his memories of his findings on an Ihan crystal and pass it on to Raynor, warning him that Kerrigan's death would be the catalyst of the future he had foreseen.

Units

 * Zealot: Templar warriors who have yet to reach the upper rankings of Khala. They serve as the Protoss' main infantry. They are brave, fearless warriors who charge right into battle without a second thought, being protected by a psionic shield and durable armour and slashing enemies with deadly Psi Blades.
 * Dragoon: The discontinued branch of Zealots who had been crippled in battle, yet volunteered to be implanted in exosuits to continue the fight. Because Aiur was abandoned and the temple dedicated to the dragoon was infested by the Zerg, Dragoons can no longer be constructed. Remaining Dragoons after the fall of Aiur were upgraded to Immortals.
 * Immortal: Those Dragoons who survived the exile from Aiur have been transformed into the Immortals, and are now retrofitted with twin phase disruptors and hardened energy shields. Because Aiur was abandoned, and the Shrine necessary to facilitate integration into a robotic shell was destroyed or corrupted, no Immortals can be built, and as more and more die on the front lines, soon there will be none left to fight. (Starcraft 2 only)
 * Dark Templar: Templar warriors of Shakuras, armed with Warp Blades, who learned to use the psionic powers of the void to combat their foes. They are able to cloak, sneak into enemy bases a obliterate everything and leave before they were even noticed.
 * Archon: Two Templar are sacrificed and merge together to form an Archon. Archons are very destructive, and possess extremely volatile psionic energies. They are able to independently deploy a powerful psionic shield, and they can rip apart enemies by directing Psionic Shockwaves. Their quotes imply a state of paradise and purity.
 * Dark Archon: Two Dark Templar can merge their souls in the same way normal Templar can, but the result is very different. They are able to create maelstroms of psionic force as well as permanently taking over an enemy's mind. Their quotes imply that their existence is a living hell.
 * High Templar: High ranking Protoss who have become experts in wielding and controlling psionic energy. They prefer to fight with their deadly psionic prowess rather than physical fighting. They can unleash devastating storms of Psionic energy that can rip a squad of marines apart in two seconds, and they can take control of enemy energy and use it against them.
 * Stalker: The Stalker is a Dark Templar's shadow essence stored inside a metal housing. They are armed with a Particle Disruptor capable of engaging both ground and aerial targets. They are also able to teleport or "Blink" a short distance away, usually to flee from advancing foes, flank enemies in an engagement, chase down fleeing enemies or pulling back an injured Stalker.

Robots

 * Probe: Small "construction" robot.
 * Reaver: A hulking, worm-like mobile factory which creates Scarab drones.
 * Observer: Small scout drones employed to record information on vast wastelands and battles for later study. Due to their complex sensor array, they have little room for weaponry, and therefore go without. However, they are capable of detecting cloaked or otherwise concealed opponents with ease, making them an invaluable asset to the Protoss war machine. While Observers built for deep space missions have no defenses whatsoever, those destined for battle are equipped with a micro-cloaking field that does not require large doses of energy to keep on for long periods of time due to its minuscule sensor signature.
 * Interceptor: Small robots built and serviced by Carriers. Aboard most of these capital ships, they serve as their only means of weaponry. They are capable of quickly bringing down hostile flight formations and can also fire potent plasma charges at ground-based targets.
 * Warp Prism: Used as a transport vessel, these robots convert both living and inorganic subjects into pure energy, with their unique signature imprinted temporarily within the prism's crystal lattice core. This process is obviously reversible. It can also be used to power Protoss structures around it, like a makeshift Pylon; however, this effect is only temporary, and the prism must revert to its transport mode within a matter of moments. (Starcraft 2 only)
 * Colossus: Striding across the battlefield on four tall, slender legs, the Colossus has a high level of mobility. Because of its massive size and the length of its legs, it is capable of stepping over and onto steep elevations such as cliffs with little difficulty, giving it a dominant field of fire. It carries two thermal lances, one mounted to each side of its chassis, which can create swathes of destruction as they burn through enemy troops. Unlike most Protoss robots, the Colossus was constructed purely as a war-machine. (Starcraft 2 only)

Spacecraft

 * Scout: Versatile air unit capable of scouting, firing anti-matter missiles and using photon blasters for ground support. Anti-matter missiles are exceptionally destructive, especially against armored targets. Scouts can further enhance their scouting ability by fitting them with Apial Sensors, allowing greater vision range. They can also add gravitic thrusters to increase their acceleration and speed. They are now gradually being phased out by the new Phoenix space fighter.
 * Corsair: The Dark Templar needed an air-to-air defender during their travels, and built the Corsair fighter. The prongs on the front of the ship focus a large amount of neutrons onto an enemy, causing weak damage, but the high rate of fire makes up for that. The pilot can focus Void energy through the neutron projector, and disrupt the firing sequences of enemy surface to air weapons.
 * Carrier: The Protoss' main capital ships, the Carriers unleash fleets of robotic Interceptors to do battle with hostile flight formations while also strafing slower ground-based targets with plasma charges. Interceptors are used to draw fire away from more important Protoss space ships. Other than this, few Carriers possess on-board weaponry.
 * Super Carrier: Few and far between, these are the Protoss' ultimate capital ships. These are heavily armed, and are likely the vessels capable of "glassing" worlds to eradicate Zerg infestations. Because these are so few in numbers, they cannot be fielded into battle.
 * Phoenix: Air-to-air spacecraft armed with twin ion cannons. They are commonly used for scouting, raiding and fighting against light enemy spacecraft due to their fast speed and extra damage to light units. Quickly replacing both the Scouts and Corsairs on the battlefield after the fall of Aiur, they are able to create an anti-gravity field capable of lifting ground units into the air, rendering them vulnerable to other anti-air fire. They are also highly maneuverable, and can fire while moving.(Starcraft 2 only)
 * Oracle: Oracles are aerial support raiders that have been recently brought into service. They use some of the most advanced Protoss technologies in existence. They are very fast, and can use Pulsar Beams to obliterate enemy mineral harvesters, and can hack enemy unit radars and sensory equipment, allowing them to track their location for a short time. They can also activate their own advanced sensory equipment temporarily for easy detection of cloaked and burrowed units. (Starcraft 2 HotS only)
 * Void Ray: A melding of Protoss and Dark Templar technologies, the Void Ray is built around a single gigantic power source: the prismatic core, which draws energy from both the psionic matrix of the Protoss of Aiur and the Void, which only the Dark Templar truly understand. When attacking, the arms "blossom" open like a flower, while the complex array of warp lenses and phase-crystals focus the core's energy into a ravening beam. As time elapses, the beam is held on its target, while three more focusing arrays work to focus two more beams, causing its devastating power to grow exponentially with the beam's intensity. It is said that the Void Ray will one day fully replace the Carriers as the top Protoss capital ship in service. (Starcraft 2 only)
 * Tempest: Brand new Protoss capital space ships that have been introduced to help the battle against the Zerg. They build up volatile energy in a Kinetic Matrix, before launching the highly charged energy particles at distant targets. These energy balls do devastating damage to enemy large flyers and capital ships. They can also use a less energy intensive Resonance Coil against ground targets. (Starcraft 2 HotS only)
 * Mothership: Constructed centuries ago, these vessels once used as primary command ships and then holy shrines now make their return as the primary command ships of the Protoss fleet, with the loss of Aiur. At their heart is a huge khaydarin crystal which has been infused with an incredible amount of psionic energy. By tapping into this energy, it can warp or even crack the very fabric of space and time itself. With this devastating power unleashed, it can wipe out entire squadrons of enemy ships in the blink of an eye, or even lay waste to entire planets. Female Templar, who up until now have not been seen in the Protoss military, are being compensated by being the only ones authorized to command these mighty vessels.