A race of four-eyed bipeds native to the world of Khar'shan, the batarians are a disreputable species that chose to isolate itself from the rest of the galaxy. The Terminus Systems are infested with batarian pirate gangs and slaving rings, fueling the stereotype of the batarian thug. It should be noted that these criminals do not represent average citizens, who are forbidden to leave batarian space by their ubiquitous and paranoid government.
Despite several disagreements with the Citadel and simmering hostility toward humans, most batarians prefer profitable pursuits such as drug running and slave grabs to out-and-out warfare. They have a reputation for being shrewd businessmen and merchants, though in more lawless regions of the galaxy like Omega, negotiations with a batarian are likely to be conducted at gunpoint.
Batarians are an anthropoidal race like humans and asari. Their faces are covered with short, fine hairs that grow longer and thicker around the mouth. A flat stripe of ridged cartilage runs along the tops of their skulls and down the backs of their necks. They have ears pointy at the upper end, though on occasion along the edges as well. The part of their faces commonly associated with the nose among humans and asari is instead an inverted flat triangle symmetrically ridged vertically. Compared to humans, batarians have a deep, guttural voice. Batarians' mouths are filled with dozens of sharp, needle-like teeth.
Their most distinctive physical feature is their four eyes, an uncommon trait among other races. One pair is set wide in prominent bony sockets protruding from the corners of their face. The second set of eyes is smaller and closer together, set higher on the face, just beneath the middle of the forehead. The eyes are uniformly dark orbs, with no discernible irises or pupils.
Batarians exhibit a wide range of skin tones and colors. Most batarians encountered by Shepard have a dark brown hue with pale facial ridges. General batarian complexions include reddish-brown, greenish, yellow-greenish to yellow-brownish, light brown, and teal.
Some batarians possess striped colorations on their heads. Observed patterns include multiple chin stripes, a single strip running from the lower lip, or a thin dagger of color above the nose. These patterns are usually colored blue, black, or red, while the nose pattern is invariably red. At least one, Balak, has what appears to be a black and yellow striped pigmentation at the temples with light green facial ridges.
Batarian blood has been observed to be red.
When the batarians achieved spaceflight, they discovered concealed Prothean ruins on Bira, a moon of Verush, that allowed them to develop FTL travel. It is a batarian point of pride that, since the ruins were damaged by earthquakes, they had less information to go on than other spacefaring races. The Citadel Council granted the batarians an embassy on the Citadel sometime after the volus, approximately a century after the batarians and Council had made first contact.
Despite being welcomed into the galactic community, batarian aggression provoked several crises in galactic relations over the years. Sometime around 1785 CE, a batarian fleet bombarded the salarian colony world of Mannovai; in 1913, the Batarian Hegemony annexed the independent asari colony of Esan; and in 2115, Citadel forces skirmished with batarian forces on the planet Enael.
In the mid-2160s, humans began to colonize the Skyllian Verge, a region the batarians were already actively settling. In 2171 the batarians asked the Citadel Council to intervene and declare the Verge an area of "batarian interest". When the Council refused, the batarians closed their Citadel embassy and severed diplomatic and economic relations, becoming an inward-looking rogue state.
Money and weapons funneled from the batarian government to criminal organizations led to many brutal raids on human colonies in the Verge, such as Mindoir, culminating in the Skyllian Blitz of 2176, an attack on the human colony of Elysium by batarian-funded pirates and slavers. In 2178, the Alliance retaliated with a crushing assault on the moon of Torfan, long used as a staging base by batarian-backed criminals. In the aftermath, the batarians retreated into their own systems, and are now rarely seen in Citadel space.
Batarians place an extremely high value on social caste and appearance, and overstepping one's place is frowned upon. Effective caste status can be bought on an ongoing basis like a subscription service, allowing the buyer to worm their way into the elite circles of batarian society given enough funds. Casting aspersions on the monetary worth of a social better is considered a serious insult. Batarians strongly believe that species with fewer than four eyes are less intelligent; they often gain the upper hand in interspecies arguments because other races find it difficult to know which eyes to focus on when speaking to them.
Slavery is an integral part of the batarian caste system, despite being illegal according to Council law. The custom is so deeply ingrained in batarian culture that batarians consider the Council's anti-slavery standing to be discriminatory. Rogue batarian slave rings are feared throughout the galaxy, especially among colonists on remote worlds, which are often raided by batarian slavers. Victims of such raids are usually implanted with control devices in their skulls, a painful operation since the slavers rarely make use of anesthetic; Talitha, abducted from Mindoir, was a victim of this practice. The batarians are also known to enslave addicts of the biotic drug red sand when they can no longer afford to support their habit.
Body language is an important part of batarian society. For example, tilting one's head to the left is a sign of admiration and respect. When a batarian tilts their head to the right, however, it is a sign that they consider themselves to be superior to the person whom the gesture was directed towards. Therefore, this gesture can easily be interpreted as an insult by batarians due to the high value that they place on social caste.
Little is known about batarian religious beliefs. Mordin Solus has noted that batarians do believe in an afterlife. When a batarian dies, his soul leaves the body through the eyes. Treatment of the corpse is considered unimportant, unless the batarian's eyes have been removed by an enemy.
In 2186, a batarian preacher asks Commander Shepard to recover the Pillars of Strength scroll so that he can guide his followers through hard times. It suggests that the batarians' religious beliefs are based on words from sacred texts, similar to some human religions such as Hinduism, Christianity, Judaism and Islam.