From Holocron - Star Wars Combine
|Average Height||1.8 meters |
|Skin color||Pale to dark brown, red, orange and yellow |
|Distinctions||Horns, facial tattoos, and two-hearts |
|Average lifespan||Lifespan: Child 1-8, Young Adult 9-14, Adult 15-44, Middle Age 45-55, Old 56-69, Venerable 70+|
|Known Members||List of known Zabraks|
Biology and appearance
This near-human species had several sub-species, each of which was distinguishable by the vestigial horns which ringed their heads. They are known for their ability to withstand great amounts of pain. The Zabrak races were native to the planet Iridonia, although were one of the first to introduce interstellar travel, and thus are widely spread around the galaxy.
These horns grew at puberty in varying patterns and signified that the time of their rite of passage was drawing near. 
The horns were one trait shared by the many Zabrak subspecies, which were divided by a number of physical characteristics that differed from subspecies to subspecies. These could include different skin tones (which included peachy white, pure white, yellow, red, tan, brown and black), horn patterns, hair growth (though it should be noted that Zabraks, unlike Humans, could not grow eyelashes or facial hair – there were some exceptions, who had eyebrows and or facial hair) and eye color (which have certain pigmentations that Humans lack, such as purple, yellow, red, and orange). 
The Zabrak, also known as Iridonians, are a humanoid species native to the inhospitable world of Iridonia in the MidRim - a world of dangerous stalking predators, deep canyons, fierce winds, and acidic seas. Zabrak resemble humans, though their heads are crowned with varying patterns of vestigial horns. For both males and females, horns begin to grow at puberty, and signal the time that their rite of passage is near. Like humans, Zabrak have different skin colors, but these hues are a result of genetic dominance. The variety of colors include a peachy white, tan, brown, and black, with many tonal standings. Zabrak can also grow hair or be completely bald, depending on subspecies. Horn patterns are often linked with hair growth (or lack thereof). Hair colors are similar to those of humans. Zabrak eye colors are also analogous to human, though yellow, purple, red, and orange are also seen on occasion.
Zabrak wear facial tattoos made up of thin lines that they receive during their rite of passage. These tattoos can be symbolic of many things, such as family lineage or where they came from, or a personal design of their own.
Zabrak are a self-assured people, confident that they can attain any goal they set out to achieve. To some they seem single-minded, being usually focused on one given idea, concept, or task at a time--with the conviction to accomplish their goal successfully. While with others such confidence might lead to prideful superiority, it isn't within a Zabrak's nature to denigrate other species. All Zabrak demonstrate great pride in their home colony, and while there is some competition among these colonies, intra- or extracultural insults or fights are not common occurrences without extreme provocation. On the contrary, most Zabrak are proud of their species' Diaspora, believing that their varied colonies and experiences add to their species' overall value to the galaxy as a whole. The motivation to make a contribution to the greater good is a driving force for many Zabrak
With instincts developed by tolerating their homeworld's environment, they are renowned warriors and explorers. Before colonizing other worlds, Iridonian clans fought continual wars to hone their skill in martial arts, and the Sith made lucrative contacts on the high council of their world, spending exorbitant sums to hire the talents of Iridonian mercenaries. While the Sith as a culture are long gone, the war-like influence remains a part of Zabrak culture, as they are still fierce, proud warriors-- particularly those from Iridonia.
Zabrak from Iridonia are culturally distinctive from their fellows from the colonies. They are more war-like overall than their cousins, and more focused on developing and passing on martial art skills to the young. Studying in the martial arts is a requirement at every Iridonian school, and those who excel in their training are sent to schools centered on the martial arts for advanced training. Some of the finest hand-to-hand combatants in the known galaxy come from Iridonia. some speculate that the species' concentration on the martial arts came from its historical connection to the ancient Sith, but the Zabrak maintain it developed from the survival and hunting needs of the people. Wealthy Zabrak from other colonies will often send their children to Iridonia to study the traditional martial arts. Zabrak also ride Iridonian reeks as battle mounts and use quarterstaves.
The Iridonian double-bladed quarterstaff, known in the Zabrak language as the Zhaboka, was first developed before the Mandalorian Wars from the scavenging of wooden sticks and metal scraps of shipwrecks. Over the centuries, the Zhaboka evolved into a well-balanced, two-meter-long staff that was tipped at each end with a tempered durasteel blade, allowing it to deal slashing or piercing wounds. The central half-meter of the staff was wrapped in leather to provide better grip. Its original use was for killing the predators found on Iridonia, although many modern Zhaboka were ceremonial weapons. The entire weapon could be unlocked at the grip and stored in a scabbard for easier transport. The use of the Zhaboka--The Zhaboka is a 2 meter long ceremonial pike with double-edged blades on either end. It used to be used in warfare, but now is seen at most special occasions such as weddings, funerals, diplomatic meetings, etc, and the Rising Festival. As befitting a warrior culture, Zabrak have one of the best reputations in the galaxy as weaponsmiths. They are known for producing some of the most reliable and powerful blasters available, along with vibroblades of uncommon quality. Zabrak weapons are valued by collectors and for personal defense, but as they are not mass produced, they are not widely used by military forces except in specialized units, such as snipers and reconnaissance.
Zabrak from other worlds exhibit a drive for excellence similar to that seen among Iridonian Zabrak, but if they do not send their children to Iridonia to study, they encourage their children to succeed in other ways. As a result, Zabrak have become highly successful in many fields, from medicine to entertainment. In addition, several Zabrak have joined the Jedi order, and two Zabrak Jedi Masters served on the Jedi Council of the Old Republic.
The Zabrak were an early spacefaring race who colonized many worlds, primarily because the Iridonian environment was so hostile. As a result, most Zabrak identify themselves by their colony world and not by Iridonia itself. They are a strong-willed people who resisted Imperial domination and are known for their incredible willpower. They are able to endure intense physical pain and torture without breaking their resolved. For this reason, Zabraks made terrible slaves, and the Imperial governors who tried to conquer them faced strong, united opposition from underground movements. They are stubborn almost to a fault, though it was this and their resolve that gave them more independence during the dark years of the Empire. Despite being made examples of for other races, having their worlds garrisoned and their industrial base largely destroyed, and being taxed into poverty and denied medical care to the point of genocide, the Zabrak resisted.
The Zabrak drive for self-determination and independence has its basis in a deep respect for life, despite their long and rich martial history or, perhaps, because of it. Zabraks were active in the galactic species rights movement even before their species was target by the Empire. 
Zabraks are capable of breeding with Humans, and a hybrid sub-species has evolved on Dathomir called the Dathomirians, formed from the mating of Zabrak males and Nightsister Humans.  Decades prior to the start of the First Galactic Civil War, a small group of male Zabrak were brought from Rattatak during a pirate raid. The Human Nightsisters discovered they could interbreed with those Zabraks, leading to the creation of the hybrid species known as the Dathomirians. The witches isolated their new slaves to a small area of the planet where they could draw from them at whim. While the Nightsisters had always kept "malelings" as labor units or mating partners, the Shaman of the Nightsisters restricted the use of males to the Zabrak Nightbrothers after becoming the leader of all Nightsister covens. She also thought it was best to keep them separated from the Sisters. A quote "While our brothers are kept separated, they are marked as our kin and our warriors by the tattoing on their chests and faces." ―Shaman of the Nightsisters Myths abound about a minute few Zabrak who have fled the Coven denouncing their former ways and living abroad in the galaxy.
Culture and personality
Considered something of a headstrong species, they are independent and capable - yet prone to biting off more than they can chew. A hardy species that can take a great deal of stress, both inner and outer, xenobiologists have varyingly tried to tie this trait to different strands in the Zabrak genetic makeup, but it seems every few years another one comes along that disproves the one before it.
Their culture is nominally broken into eight major colonies, and each Zabrak is said by Iridonian law to belong to one of them. However this is often muddied by the interbreeding brought about by their great travels across the galaxy, and today it is not uncommon to find a Zabrak who claims membership in as many as five of the different colonies.
Zabrak were often seen by most other species as being single-minded, an observation that was not terribly incorrect. This single-minded determination came from the fact that they were a race with a strong sense of self-assuredness, confident that they were able to accomplish any task that they set out to do. However, this did not lead a Zabrak to develop a sense of prideful superiority towards others, though there was often the occasional competition between colonies. This was not seen as a negative, however, for the Zabraks believed that the various experiences of the different colonies only served to add values to the race's overall value to the galaxy. 
Zabrak from Iridonia were considered to be more war-like than Zabrak from their colony worlds, most likely due to the rugged terrain that made up their home world. As such, they developed a highly physical style of martial arts, which were a requirement for young Zabrak to learn. It was not uncommon for Zabrak from Iridonia to be among the best hand-to-hand fighters and weaponsmiths in the galaxy. Zabrak from colony worlds also shared that drive for excellence, but encouraged their children to express it in other ways. It was thus not surprising to see that the Zabrak met with success in many fields, ranging from medicine to entertainment. 
Zabrak would commonly take their names from animals native to Iridonia, with many Zabrak families named after the Bukk. Many Zabrak males were named after the Blok, Lok, and Zur. Many Zabrak females were known to take their names from the Triz.
As one of the earliest spacefaring species in the galaxy, the Zabrak played a major role in Galactic affairs. Like the early Humans, the Zabrak established many colonies outside their home system early in their history, such as on the planet Iridia. The Elomin species was believed by some xenoarchaeologists to be descended from Zabrak colonists who settled Elom in the distant past. By the time the Zabrak encountered the Republic, they had a total of eight colonies in five systems. 
Long ago, the Sith had made contacts with the high council of Iridonia in order to hire the services of their most talented mercenaries. This influence remained with the Zabrak people long after the Sith were thought to be wiped out, though it remained more closely associated with the Zabrak of Iridonia than the Zabrak of their colony worlds. 
Iridonia is ill-suited to support humanoid life, with most of the farm-able land located in canyons through which strong winds race, sometimes reaching over 200 kilometers per hour. Seas of acidic liquid swirl up into acid spouts that soar hundreds of kilometers before splashing down onto highland villages and fields perched atop the sea cliffs. Worse, gigantic predators occasionally emerge from the depths of the acid seas to swallow ships whole or destroy settlements.
The harshness of their world forged in the Zabrak an iron will to survive. Driven to escape their world they saw the glittering lights in the night sky as an escape. Their civilization was eventually completely dominated by the urge to first scale the highest peaks, then to fly, then to obtain space flight.
The Zabrak colonies were settled by the most independent of the strong-willed people, so each of them considered itself a sovereign system. However, each colony, and the Zabrak itself, saw the value of Republic membership from the start. For millennia, the Zabrak-settled worlds marked a galactic frontier.
No one knows how Zabrak came to be on Iridonia. There are myths of the gods bringing the Zabrak to Iridonia, implying that we actually began somewhere else. We have a very warlike history, and for many generations clan wars raged until we realized that we needed to have peace in order to survive on our planet.
Iridonia is very inhospitable, and as soon as our people discovered spaceflight, there were many waves of explorers who left. The descendants of these explorers make up the majority of Zabrak alive today. Several colonies were formed first on the planets near Iridonia, then eventually spreading out to the edges of the galaxy. There are also numerous Zabrak space stations. These grew in size, and most Zabrak identify themselves with the colony or station their people are from, rather than having any ties to Iridonia. Each colony at first considered itself a sovereign state, however when the Republic was formed the Zabrak colonies were among the first to send delegates to the new Senate.
There are a large number of Zabrak who are descendants of those who made their way to the Outer Rim or other planetary systems. The largest colonies of this type were on Talus and Corellia. Most of these Zabrak that I have met have only the simplest knowledge of traditional Iridonian customs, such as the facial tattoo. There are some with no knowledge of clan, or who have clan surnames that were passed along by parents or obtained through marriage.
With the coming of the Empire, garrisons were placed on all Zabrak-settled worlds. These were greeted in a variety of ways, from sullen acceptance to active armed rebellion. The Empire reacted by placing heavy taxes on Zabrak worlds and trade routes, crushing revolts, and generally making an example of Zabrak populations.
References:  - http://starwars.wikia.com/wiki/Zabrak (to include numerous articles and research from the Zabrak Historical Society)