The Asari, native to the planet Thessia, are known for their elegance, diplomacy, and psionic aptitude.

A mono-gender race, the Asari are distinctly feminine in appearance and possess maternal instincts. Their unique physiology, expressed in a millennia-long lifespan, gives them a conservative yet convivial attitude toward other races.

A typical Asari individual has a blue to purple complexion; the gas giant Sharblu was named after a famous Asari soprano with a distinctive skin tone that resembled the planet's atmosphere. Some Asari can also have a teal complexion, but this seems to be a rarity. Some Asari have facial markings, which are unique color patterns that vary for every Asari. Some of these facial markings are associated with eyebrows by humans, but the Asari do not think of the markings as such themselves. In the place of head hair, Asari possess semi-flexible, cartilage based scalp crests that grow into shape. These structures are rigid, and do not “flop around” as some believe. Asari also have a robust cellular regenerative system; they are known to reach over 1000 years of age. Asari blood is purple.

Uniquely, the Asari are known to be perceived as attractive to many other species.

There is some conflicting information regarding the gender of the Asari. Though they resemble females, at least to humans, Asari are non-gender specific, with no concept of gender differences. The species is mono-gendered so male and female have no real meaning for them. But by the general definition of gender they are thus female.

Although they have one gender, they are not asexual. An Asari provides two copies of her own genes to her offspring, the father is the one who does not give birth. The second set of genes is altered in a unique process called melding, also known as the joining.

During melding, an Asari consciously attunes her nervous system to her partner's, sending and receiving electrical impulses directly through the skin. A common phrase used before melding is “embrace eternity,” presumably to help focus the partner's mind. Effectively, the Asari and her partner briefly become one unified nervous system. This unique means of reproduction is the reason Asari are all talented Psionics. Their evolved ability to consciously control nerve impulses is very similar to psionic training.

An Asari's melding ability extends to a mental connection as well, which is described as being the true union between an Asari and her partner. It allows the Asari to explore her partner's genetic heritage and pass desirable traits on to any offspring. During mating an Asari and her partner share memories, thoughts, and feelings. It is also possible for an Asari to meld with another for the sole purpose of transferring thoughts, without reproduction.

Asari pass through three climacteric life stages, marked by biochemical and physiological changes:

• The Maiden stage begins at puberty and is marked by the drive to explore and experience. Most young Asari are curious and restless, and it is not uncommon for many to try their hand at dancing in bars or working as mercenaries during this time.
• The Matron stage of life begins around the age of 350, though it can be triggered earlier if the individual melds frequently. This period is marked by a desire to settle in one area and raise children.
• The Matriarch stage begins around 700 years of age, or earlier if the individual melds rarely. Matriarchs become active in their community as sages and councilors, dispensing wisdom from centuries of experience. Their knowledge and guidance may be one reason why Matriarchs are rarely seen outside Asari space.

However, it should be noted that each stage can be started whenever an Asari feels that she has reached the correct level of maturity. While each stage of life is marked by strong biological tendencies, individuals do make unexpected life choices. For example, there are Maidens who stay close to home rather than explore, Matrons who would rather work than build a family, and Matriarchs who have no interest in community affairs.

The Asari arose on Thessia, a rich world with abundant resources.

Because of their long lifespan, Asari tend to have a “long view” not common in other races. When they encounter a new species or situation, the Asari are more comfortable with an extended period of passive observation and study than immediate action. They are unfazed that some of their investments or decisions may not pay off for decades or centuries. Matriarchs can seem to make incomprehensible decisions, but their insight is evident when their carefully-laid plans come to fruition. In interstellar relations, this long view manifests in the unspoken policy of centrism. The Asari instinctively seek to maintain stable balances of economic, political, and military power.

Traditionally, Asari spread their influence through cultural domination and intellectual superiority. The Asari tend toward communal, consensus attitudes among themselves: for example, they prefer to live in shared spaces aboard starships even if there are alternatives available.

Asari believe that their offspring acquire the best qualities of the “father” from the melded genes, but evidence is anecdotal.

Asari are well aware they tend to be attractive, and are comfortable expressing their sexuality, as can be witnessed in places like Chora's Den or Afterlife with Asari erotic dancers. Young males of other races tend to have a fascination with Asari.

Because of their natural sensuality, Asari are sometimes rumored to be promiscuous. These rumors are mostly a result of misinformation (or wishful thinking). Therefore, they have had to apply their philosophical “long view” to relationships as well, savoring the time they spend with their partners rather than focusing on their inevitable loss.

The Asari celebrate the springtime fertility ritual Janiris, named for the goddess Athame's guide Janiri, which marks the start of the new year. During this time, they create wreathes of flowers and distribute them among their friends and loved ones.

A few Asari abandon all but a few personal possessions to become justicars, members of an ancient order of Asari adhering to a strict code. Justicars operate inside of Asari space correcting injustices, often through harsh means, including death. It is rare for a justicar to leave Asari space as it could cause a diplomatic incident with other species.

The Asari possess the third largest known economy in the known parts of the galaxy(behind the Empire and The Turians). They have extensive trade and social contacts. Craft guilds, such as those within the cities Serrice and Armali, hold a virtual monopoly on advanced technology.

The pantheistic mainstream Asari religion is siari, which translates roughly as “All is one”. The faithful agree on certain core truths: the universe is a consciousness, every life within it is an aspect of the greater whole, and death is a merging of one's spiritual energy back into greater universal consciousness. Siarists don't specifically believe in reincarnation; they believe in spiritual energy returning to the universal consciousness upon death will eventually be used to fill new mortal vessels.

Siari became popular after the Asari left their homeworld and discovered their ability to “meld” with nearly any form of life. This ability is seen as proof that all life is fundamentally similar. Siari priestesses see their role as promoting unity between disparate shards of the universe's awareness.

Before the rise of siari pantheism, Asari religions were as diverse as their political opinion. The strongest survivor of those days is the monotheistic religion worshipping the goddess Athame. Like the Asari, the goddess cycles through the triple aspects of maiden, matron, and matriarch. Asari often swear “by the goddess”, though this may be a cultural legacy rather than reflecting an individual's belief.

The Asari governmental structure, known as the Asari Republics, is relatively broad; the Asari came late to the notion of world government. For centuries, their homeworld of Thessia was dotted with loose confederacies of great republican cities. The closest Human equivalent would be the ancient Mediterranean city-states. Since the Asari culture values consensus and accommodation, there was little impetus to form larger principalities. Rather than hoard resources, the Asari bartered freely. Rather than attack one another over differing philosophies, they sought to understand one another. Only in the information age did the city-states grow close; communication over the internet evolved into an “electronic democracy”.

The Asari have no politicians or elections, but a free-wheeling, all-inclusive legislature that citizens can participate in at will. Policy debates take place at all hours of the day, in official chat rooms and forums moderated by specially-programmed virtual intelligences. All aspects of policy are open to plebiscite at any time. In any given debate, the Asari tend to lend the most credence to the opinions of any Matriarchs present, nearly always deferring to the experience of these millennia-old “wise women”.

The Asari military resembles a collection of tribal warrior bands with no national structure. Each community organizes its own unit as the locals see fit, and elect a leader to command them. Units from populous cities are large and well-equipped, while those from farm villages may be only a few women with small arms. There is no uniform; everyone wears what they like. The Asari military is not an irregular militia, however; those who serve are full-time professionals.

The average Asari huntress is in the maiden stage of her life and has devoted 20-30 years studying the martial arts. Asari choose to be warriors at a young age, and their education from that point is dedicated to sharpening their mind and body for that sole purpose. When they retire, they possess an alarming proficiency for killing.

Huntresses fight individually or in pairs, depending on the tactics preferred in their town. One-on-one, a huntress is practically unbeatable, possessing profound tactical insight, a hunter's eye, and a dancer's grace and alacrity. Psionics are common enough that some capability is a requirement to be trained as a huntress; lack of Psionic talent excludes a young Asari from military service.

While fluid and mobile, Asari units can't stand up in a firestorm the way a Turian or Human could. Since their units are small and typically lack heavy armor and support weapons, they are almost incapable of fighting a conventional war, particularly one of a defensive nature. So Asari units typically undertake special operations missions. Like an army of ninja, they are adept at ambush, infiltration, and assassination, demoralizing and defeating their enemies through intense, focused guerrilla strikes.

As a popular Turian saying puts it, “The Asari are the finest warriors in the galaxy. Fortunately, there are not many of them.” Despite this, the Asari military is still very large.

The Asari possess one of the most powerful navies in the known parts of galaxy. Despite the considerable force of numerous dreadnoughts they can bring to bear, the Asari prefer using fleets composed mainly of frigates and fighters, embodying their hit-and-run mindset with a nimble swarm rather than a slower collection of vessels.