"It is as we join with others, in a way that only Tau can, in shared engagement to the Greater Good, that we find ourselves able to fully realise our true potential. And that is the final source of our hopes and inspirations."
— Aun'el T'au Tam'ya, Ethereal Caste
Ethereal Icon

The symbol of the Ethereal Caste


A Tau Ethereal leading the Fire Caste from the frontlines

An Ethereal is a member of the fifth caste of the Tau species, forming a ruling elite above the Fire, Earth, Air, and Water Castes that make up the bulk of the Tau population. Known as the Aun in the Tau Lexicon, their name translates variously as the Celestial or Ethereal Caste. Though their numbers are small compared to the other castes, the Ethereals are the rulers of the Tau Empire, and command near total authority and loyalty from every other Tau. Born to counsel, advise and steer their comrades towards the chosen path, the Ethereals embody the roles of royalty and the priesthood, and the deference paid to them is the closest thing to mysticism in Tau society. For weighty decisions, a wise Ethereal will take counsel from the senior members of each caste, although ultimate sovereignty falls upon him and him alone. The Ethereals find themselves in a binding role -- guiding the other castes to work together for the Greater Good, and they are headed by a council on T'au of the wisest Ethereals. Their unique role is a combination of spiritual and political command, and their declarations shape and steer every facet of the Tau Empire in an indisputably complete way. An Ethereal must be a consummate leader and motivator in every way: pushing the Earth Caste for more practical innovations, setting firm negotiation goals for the Water Caste to strive for, giving perimeters to the great fleets of the Air Caste and directing the sometimes overzealous aggression of the Fire Caste.


"Those whose time is brief must surely strive all the harder, that the universe shall remember their deeds."
— Aun'O Quva, Tau Ethereal

An Ethereal of Fio'taun preaches the Greater Good

The Ethereal Caste first came into existence during the phase in the Tau species' earliest history in which the four castes were at war with one another, the entire species apparently doomed to destroy itself in its own birth pangs. In this period of turmoil known as the Mon'tau, the Ethereals appeared as from nowhere, and ended the conflict with a single command. They have ruled ever since that time. The Ethereals of Fio'taun is the most well-known legend of that time, and is known by all Tau in the Tau Empire, for it tells of how the Tau were held back from the brink of self-annihilation.

The Ethereals of Fio'taunEdit

When the Tau entered their darkest age as the 37th Millennium of the Terran calendar drew to a close, and the entire race was being destroyed by war and disease, many strange portents and omens were observed such as flickering lights in the night sky and half-glimpsed figures in the mountains. Many believed that these were the signs that they were living in the last days, that extinction was nigh.

The legend tells that on a mountain plateau called Fio'taun, an alliance of plains dwellers and air Tau laid siege to the mightiest fortress-city of the builder Tau. Nearly seven thousand beings dwelt in the great citadel and, in vain, the traders attempted to negotiate with the plains warriors. The plain warriors' blood was afire though, and they would brook no settlement save that delivered at the end of a rifle. For five seasons the cannons of Fio'taun held the attackers at bay, but supplies were running low and disease was rife within the city walls. As night fell upon another bloody day of fighting, the leaders within Fio'taun prayed for a miracle. Little did they know that on this night their prayers would be answered.

Emerging from the darkness, a Tau of unusual appearance walked into the besiegers' camp, asking to see the army's commander. He was softly spoken, yet it is said that he had an undeniable authority. The sentries to whom he had announced himself found themselves compelled to escort him to their leader. At the same time, within the walls of Fio'taun, a similar individual presented himself to the guards of the fortress. How he had penetrated the defences of the city he would not say. All he asked was that he be allowed to speak to the castellan of the fortress. Again, his request could not be denied and he was permitted an audience with the city's leader. Within the hour, the fortress gates were opened, the stranger guiding the citadel's leaders towards the torchlit camp of their attackers.

As the gates opened, they were met by a party from their enemy, led by a figure who was the stranger's twin in all respects. The two newcomers called themselves Ethereals and bade the others sit. Beneath a maiden moon of purest white, they began to speak, explaining that the talents of each of the tribes could be harnessed. They spoke of a Greater Good that could be achieved if they would put aside their warlike ways and worked together. The two strangers talked through the night, their words carrying great power, and as the sun crested the horizon, a truce had been agreed between the warring factions.

Fio'taun was just the beginning. Soon, more of the Ethereals emerged and the message of peace and the Greater Good began to spread to every corner of the globe of T'au, the battles slowly dying out as the new philosophy took hold. Within the space of a solar year, the wars were over and the Tau flourished like never before. Well-constructed towns and cities sprang up throughout the continent, commerce routes were re-established by the traders and communications maintained by the air Tau. The warriors of the plains were the hardest to convince that this was the way forwards, but as they saw the civilised wonders being created by the other castes, they finally agreed to the Ethereals' entreaties and became honour-bound defenders of the Tau. It was decreed that from that day forth each of the tribes would be known by the element that most befitted its role in the Greater Good. The builders and artisans would be the Earth Caste, the traders the Water Caste, the messengers and scouts would become the Air Caste, while the warriors of the plains would be known as the Fire Caste. Having saved the Tau from a slow racial extinction, the Ethereals were revered with utmost devotion by the other castes, binding and guiding them as they looked towards the future with a newfound sense of hope.


"Wherever we have cast our gaze in this galaxy, we have seen only the dead and the dying, and those intent only upon casting themselves into burnings pyres of their own making. That is why we shall ultimately prevail, for we are different. We are united, we are determined, and we cannot fail but embrace the manifest destiny into which we are born."
—Aun'Talusi, Tau Ethereal and philosopher

An Ethereal provides inspiration to his troops

In temperament, Ethereals are enigmatic and studious, yet unfaltering in their authority and their drive to further the Greater Good. They are mystics and philosophers, possessed of knowledge and wisdom not shared by their more practical subjects. The origins of the Tau species are shrouded in mystery, and it is a great enigma that the Tau ascended from the status of primitive nomads to a highly developed, star-faring empire in less than six Terran millennia. The Ethereals evidently had some part to play in this rapid development, and to this day guide their species in its dynamic expansion lest the castes revert to the savagery that once threatened to overwhelm it.

The Ethereal Caste organises itself using the same system of ranks as do the other four castes, with the lowest formed into councils overseeing settlements, and the highest ruling over entire Septs -- autonomous and self-sustaining Tau colony systems. The caste as a whole is guided by a body referred to as the Council of the Highest, also known more simply as the High Council, consisting of all of the most senior Ethereals in the Tau Empire. No single individual heads this council, and it tends to be guided by the wisdom of whichever Ethereal is regarded by his peers as pre-eminent at the time. The High Council is based on the Tau homeworld, T'au, and from here orders and edicts are issued and are followed without question by all across the Tau Empire, for the Ethereal Caste members who issue them are revered by countless billions, and their wisdom is beyond doubt.

Some Ethereals have been known to accompany Tau forces into battle, and indeed a number always accompany Tau colonisation and expansion forces. It has been theorised by Imperial scholars that Tau, especially those of the Fire Caste, not operating under the high-level guidance of an Ethereal are likely to regress to the warlike state that so nearly destroyed their species at the dawn of its history. Needless to say, there are those amongst the Imperium keen to investigate this matter further, in the hope that targeted assassination of key Ethereals might bring about a favourable strategic situation. It is not necessary for Ethereals to participate in every conflict at the tactical level, as Fire Caste warriors are quite capable of operating without them being close at hand. It appears, however, that an Ethereal should be present at the operational or strategic level to ensure the stability of those under his command.


Aun'shi fights against the Ork foe

Very rarely, Ethereals participate in a battle to provide inspirational leadership, in order to push the warriors on to achieve otherwise impossible things in the name of the Greater Good. The presence of an Ethereal is not as a mere figurehead; they are also reverential leaders for whom any Tau would willingly lay down his or her life. By invoking the elemental truths, an Ethereal can inspire those around him to perform feats above and beyond what is normally considered possible -- bravery in the face of certain death, an increased focus as enemies draw near, an ability to withstand crippling pain or a sudden celerity that allows them to maintain a weight of fire even on the move. The Tau themselves do not question the source of these powers, accepting the greatness of their leaders on faith. There is a downside to this, however, for should the Ethereal fall in combat, the remaining Tau may be consumed with maddening grief. Sometimes they collapse in total disarray, even if they could easily have won the engagement. Other times they overcome their dismay and become filled with anger, fighting all the more furiously against the enemy in order to take revenge for their loss. When this happens, the Tau do not run forward into barbaric close combat but instead advance slowly, steadily pouring ever greater amounts of firepower into the enemy. In order to prevent the loss of an Ethereal in battle, they are usually accompanied by an Honour Guard of veteran Fire Warriors who have chosen to forgo the normal progression to Battlesuit pilot and then Tau Commander. These Fire Warriors are dedicated in their role of protection of their Ethereal, and will gladly lay down their lives to save his.

The method by which the Ethereals maintain control over their species is unknown to the Imperium, and possibly even to those they rule. Many assume such manipulation is a form of innate psychic ability; others feel that the faultless loyalty the Ethereals inspire has been contrived by some unseen technology, or is even the result of some pheromone-based reaction. The most primitive races Tau forces have encountered believe the Ethereals are deified beings, leaders of an advanced people chosen for greatness. Naturally, the Ethereals themselves help propagate and encourage this particular myth. As the Tau do their utmost to prevent any Ethereal from being slain or captured, there have been few opportunities to conduct tests, and those that have been performed offer no conclusions, and far more questions. Indeed, several studies have been undertaken by the Imperium, and the Ordo Xenos Deathwatch is even in the possession of a low-ranked member of the caste having captured him as his vessel passed through an unclaimed system near Tau-controlled space. Prior to the capture of this specimen, it was assumed that the Ethereals must utilise some unidentified method of biological, psychic or even pheromone control over the Tau. The Ethereals sport an unidentified organ in the centre of their foreheads, a smaller version of which is possessed by other castes. It was assumed that this organ must be key to the control effect, yet the specimen captured has been extensively examined and no functioning system has been identified. Either the captured Ethereal is a deliberate attempt to misdirect the Imperium, or the matter is far more esoteric than had previously been thought.

Notable EtherealsEdit

Aun'El Basel'kyth Suspected by the Imperium to be the head researcher/philosopher of Tau forces in the Jericho Reach, Aun'El Basel'kyth is currently thought to be located in the Beldar Academy on the planet Tsua'Malor.
Aun'Ui Kol'denh Aun'Ui Kol'denh is a social engineering advisor for Tau forces in the Jericho Reach. He has a personal armoured anti-grav unit with a life-support system, possibly due to deteriorating health, and is currently thought to be located in the orbital installation Iphigenia.
Aun'El T'au Ko'vash Aun'El T'au Ko'vash was an Ethereal captured by Imperial forces and held captive by Governor Severus on the planet Dolumar IV. He was eventually freed by Shas'la T'au Kais but captured again the same day and killed by the Heretical Governor Severus.
Aun'Ro'Yr Aun'Ro'Yr was the Ethereal who accompanied Shas'O Or'es'Ka during the Kaurava Campaign. His ultimate fate is unknown.
Shas Aux'Phan Shas Aux'Phan was a Tau Ethereal who died during the Auxion Campaign at the hands of the Dark Angels Ravenwing Grand Master Sammael.
Aun'shi A modest hero of many battles, Aun'shi longs for peace but is bound by duty to his comrades to wage war. Lionised by the Fire Caste, he is seen as a sure sign of victory upon the battlefield, and is greeted everywhere he travels with many salutes and deep and respectful bows.
Aun'El Shi'Ores Aun'El Shi'Ores was the accompanying Ethereal of Shas'O Kais during the Dark Crusade to take the planet Kronus. He was killed by Blood Ravens forces, but his body was retrieved by Shas'O Kais and returned to T'au for burial.
Aun'taniel Aun'taniel was the head Ethereal of the Tau colony of Ka'mais. When a Necron fleet destroyed the Tyranids of Hive Fleet Gorgon about to consume the world, Aun'taniel went out to greet the colony's saviours. In this first contact scenario between the Tau and Necrons, Aun'taniel was subsequently killed.
Aun'la Tsua'Malor Vior'la Aun'la is a low-ranking Ethereal Caste member who was captured by a Deathwatch Kill-team from a courier craft in-transit. In an exceptionally tricky operation undertaken by Battle-Brother Pellas, the Gladius-class Frigate Thunder’s Word slipped deep into Tau-controlled space and intercepted the Aun's craft as it passed through an uninhabited star system. Precision weapons fire crippled the smaller ship's drives and a boarding party easily overpowered the xenos inside. The courier craft was rigged to suffer a catastrophic drive failure and the Thunder’s Word disappeared into the void without sighting any other Tau voidships. As far as is known, the Tau are unaware that the Aun has been captured and believe him to have been killed in the accidental explosion of his ship.
Aun'O Tsualal An Ethereal strategist for Tau forces in the Jericho Reach, Aun'O Tsualal is currently participating in combat in the Velen battlezone of the Greyshell Front. He is the overall commander of all Tau forces in the region and on Tsua'Malor, and his armoured grav-unit always has a Fire Caste bodyguard and Shield/Gun Drone squadron protective detail at all times.
Aun'Va It is said that Aun'Va, Master of the Undying Spirit and the most recent Ethereal Supreme, was the oldest and the wisest of his caste. He had counselled the greatest leaders of the Tau for longer than any can recall, and his hand was seen at work behind much of Tau history. He was the most senior Ethereal upon T'au, sitting upon the councils that ruled not just the Sept but the entire empire. His word was heeded by every member of his caste, for his council had ever proven wise and true. He eventually met his fate at the hands of a Culexus Assassin, who was sent to the beleaguered Imperial world of Agrellan Prime as a part of an Officio AssassinorumExecution Force, which occurred during the Second Agrellan Campaign.
Aun'Vre Aun'Vre was the Ethereal who accompanied Shas'O R'myr during the Taros Campaign, helping to oversee the Tau conquest of the planet. He was killed by the death explosion of an Eversor Assassin within the Tau command centre, though his death sparked a vengeful counterattack by the Tau on the evacuating Imperial forces.
Aun'Wei Aun'Wei was an Ethereal Supreme and the predecessor of Aun'Va. He oversaw the Second Sphere Expansion of the Tau Empire. After a long rule, Aun'Wei chose Aun'Va as his successor and undertook the Last Walk, the ceremony where an ancient member of the Ethereal Caste disappears forever within one of their mysterious temple-domes.


In battle, Ethereals are typically armed with either:

  • Honour Blade – Honour Blades, whilst custom-made to each individual, all consist of a long, broad-bladed halberd mounted on a lightweight metallic shaft. Honour Blades serve as symbols of an Ethereal's office, ceremonial weapons and, in emergencies, weapons of self-defence. Honour Blades are typically used to settle disputes between Ethereal Caste members in highly stylised, bloodless duels that are more coordinated co-meditation than combat. In the hands of an Ethereal, Honour Blades are used in elegant sweeping movements where the blade becomes virtually invisible. Whilst some Ethereals carry their Honour Blade onto the field of battle, they do not expect to have to actually use them, but are nevertheless prepared to make a last stand against their barbaric foes if the situation should require it.
  • Equalizers - Similar in appearance to batons, Equalizers are carried in pairs and serve as badges of an Ethereal's office, and also double as potent self-defence weapons. Each Equalizer contains a powerful disruption field that can shatter armour and bone on impact.

Ethereals can also be equipped with a Blacksun Filter and/or Homing Beacon, and are commonly accompanied by a pair of Shield Drones that are programmed to protect them by physically blocking incoming shots or blows if necessary. Less often, up to a pair of Marker Drones or Gun Drones may be found accompanying them instead.


  • Codex: Dark Angels (6th Edition) (Digital Edition), pg. 79
  • Codex: Tau (6th Edition), pp. 7, 9, 35, 60-61, 97
  • Codex: Tau (4th Edition), pp. 5-6, 9-10, 28, 33, 42-43, 65
  • Codex: Tau (3rd Edition), pp. 5-6, 9, 19, 23, 52
  • Codex: Tyranids (5th Edition), pg. 21
  • Deathwatch: Core Rulebook (RPG), pg. 355
  • Deathwatch: Mark of the Xenos (RPG), pp. 11-12
  • Deathwatch: Rites of Battle (RPG), pg. 240
  • Imperial Armour Volume Three – The Taros Campaign, pg. 283
  • Fire Warrior (Novel) by Simon Spurrier


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