Cardassians are a spacefaring race in the fictional Star Trek universe. The Cardassian Union was introduced in the Star Trek: The Next Generation episode "The Wounded". Cardassians were one of the main parts of the storyline in Star Trek: Deep Space Nine. The Cardassian homeworld is Cardassia Prime in the Alpha Quadrant.
The Cardassians were conceived by the writers to provide an enemy race with whom the protagonists could interact, unlike the Borg where such drama is difficult due to their lack of personality and individualism.
A major figure in Cardassian history is Tret Akleen, revered as the "father" of the Cardassian Union. During the Dominion War, Akleen's family home lay in Dominion-controlled space; Elim Garak suggested that recapturing it would lead to a major propaganda victory for Federation forces. ("Tears of the Prophets")
Although the Cardassian Union was referred to as an "empire" on more than one occasion, little if anything is known about which races (aside from, for some decades, the Bajorans) the Cardassians have conquered in their imperial ambitions. Prior to joining the Dominion, the Cardassians had no strong allies among other major powers but enjoyed comparatively good relations with various non-aligned species, such as the Lissepians, as mentioned in "Progress", "Indiscretion", and other episodes.
Their skin is tan or gray in color and hair is dark brown or black. Their eye color is usually dark-brown, however there are some exceptions to this rule, such as Gul Dukat and Garak, who have blue eyes. Since scale patterns on Cardassian necks have been shown to change from appearance to appearance (Garak, for example), makeup artist Michael Westmore has theorized in a 2005 issue of Star Trek Insider that Cardassians continually shed and regrow scales. In the episode Profit and Loss, an intimate encounter between Quark and his starcrossed lover Natima Lang displayed that stroking the neck ridges of a Cardassian female produces an erogenous reaction. Whether this is true for males has not been explored. Female Cardassians have blue-tinted spots on their neck ridges and forehead.
Compared to humans, Bajorans, and many other humanoid races, Cardassians prefer warmer and darker climates. Elim Garak once noted that Deep Space Nine's environment was very cold and very bright by Cardassian standards.
Cardassians have a wide variety of food and drink that they enjoy:
In an episode of Deep Space Nine, Elim Garak mentions that Cardassians do not have as good a sense of hearing as do humans (DS9 "Distant Voices").
Cardassia's educational system is legendary throughout the quadrant. From a very young age, Cardassian children are trained in techniques such as photographic memory which allow them to retain vast amounts of information. Cardassian mental disciplines are rumored to be so complete that a Cardassian will prove almost totally resistant to torture; a Vulcan mind meld is also usually ineffective against a Cardassian who is properly trained.
Cardassians generally believe the state is more important than the individual. Certainly their Orwellian government is powerful and the intelligence service, the Obsidian and Fourth Orders, excels in ruthless efficiency. Cardassians seen on Deep Space Nine are generally proud and patriotic, and reference is occasionally made to their xenophobic tendencies, although they are often seen co-operating with other races with no apparent friction. In many ways Cardassian society loosely mirrors that of the Soviet Union, everything from the name of the empire, the system of government, the prominence of the military in society, the ruthlessly efficient intelligence service, the lack of respect shown for the justice system, and the acts and omissions made criminal by the empire. When representatives of the science ministry visited DS9 in "Destiny", they were noticeably less nationalistic than most Cardassians seen previously.
They are generally cunning and suspicious. This is evident in battle, as evidenced in "Soldiers of the Empire" in which a Klingon speaks admiringly of Cardassian adversaries who always had 'a plan within a plan within a plan leading to a trap'. A popular Cardassian board game is 'Kotra', which, as Garak describes it, favors bold tactical manoeuvres over defensive play; hence Garak's criticism of Nog's attempts to regroup his pieces during a game they played in the episode "Empok Nor".
In Cardassian criminal trials the defendant is presumed guilty and in fact the punishment is already decided before the trial begins; the purpose of the trial (effectively a show trial) is merely to help the defendant acknowledge his wrongdoing. In Cardassian mystery novels, everyone is always guilty, the puzzle being to work out who is guilty of what. In Cardassian mythology the Galor deity was a helmeted, warrior demi-god of antiquity. Tribute is paid to the vessel class of the same name as well as the likeness seen in the national symbol.
Cardassians are also very concerned about their families. For example, Garak enters a Dominion prison camp to speak with his father, Enabran Tain, one last time before Tain died. In another incident Gul Dukat is driven insane when his daughter Tora Ziyal dies. In Cardassian society, advanced age is seen as a symbol of power and dignity; in Cardassian families, it is common for many generations to live together under one roof. Also, an old Cardassian tradition is that of shri-tal, an ancient ritual in which a dying person reveals his or her secrets to the rest of the family, for use against their enemies.
Cardassian literature often confounds humans, and vice-versa. For example, humans see all Cardassian mystery stories as having an identical plot: the inevitable result is that all the suspects are eventually proved guilty of the crime and proving the supremacy of the state. One of their most revered forms of literature is the repetitive epic, which traces a family throughout history, focusing on each generation's virtually identical allegiance to the state. (see: "The Never-ending Sacrifice", one such epic in Elim Garak's collection. The fictional plot focuses on the protagonist's lifelong duty and commitment set against the "oppressive tyranny" of the Klingon Empire.) Conversely, most Cardassians figure out during the first act of Shakespeare's Julius Caesar that all the conspirators are going to kill him, but cannot understand why Caesar cannot figure this out (or is willfully blind to an impending coup d'état) until the knives are literally coming at him from all directions.
The Obsidian Order frequently clashed with Central Command (the Cardassian military), partly because even the highest ranking Command officers are not immune from Order inquiries. According to the Cardassian governmental charter, the Order is expressly forbidden from developing or possessing military equipment of any kind. (DS9: "Defiant") Elim Garak was a member of the Order, before being exiled from Cardassia to Deep Space Nine by his father, Enabran Tain. Tain had retired for a time, the only director to ever live long enough to do so. Garak became an ally of the Federation who used his knowledge to aid them in the war against the Dominion. In 2371, the Obsidian Order and their Romulan equivalent, the Tal Shiar, allied in an attempt to destroy the Dominion. To this end, the Order began stockpiling a fleet of ships, even though its governmental charter strictly forbade it from possessing or developing military equipment of any kind. The plan, originated by Tain, involved a fleet of cloaked Romulan and Cardassian vessels traversing into the heart of Dominion territory in the Gamma Quadrant where they would annihilate the homeworld of the Founders.
The Founders soon learned of the plan and saw it as an opportunity to eliminate the two dangerous organizations. When the Romulan/Cardassian fleet arrived at the Founders' homeworld, they bombarded it, only to realize that the planet was deserted except for a token beacon. Moments later, the Dominion sprung the trap they arranged and a fleet of 150 Jem'Hadar fighters emerged from hiding in a nearby nebula and proceeded to wipe out the fleet. At least a few Romulan and Cardassian officers survived to be taken prisoner. Tain himself survived for two years in a Dominion internment camp before dying of heart failure. The disastrous results of this attack (and perhaps fear that the Order had clearly become too independent) led to the downfall of the Obsidian Order. The downfall of the Obsidian Order is thought to have contributed to a political shakeup that led to the renewed empowerment of the Detapa Council. This in turn paved the way for invasion of Cardassia by the Klingon Empire and eventual Dominion membership. After Cardassia joined the Dominion, an organization similar to the Obsidian was formed, which was called the Cardassian Intelligence Bureau.
The Cardassian Central Command uses a system of hierarchical ranks, which is the same for all branches of the service. A garresh is the lowest-ranked soldier, the rank where all new recruits start. Garresh make up the vast bulk of the military. They are individually ranked on a five-number scale. The lowest commissioned rank is that of gil (sometimes seen as kel), followed by glinn, dalin, dal, and gul.
Officers must generally hold a rank of at least glinn to be given command of a department on board a starship or within a unit. Larger vessels and units require dalin or dal level officers. Guls are the rough equivalent of Starfleet captains. They are the majority of the commanding officers in Central Command, controlling starships and bases, and serving as prefects and planetary governors throughout the client worlds of the Union. Many guls are quite influential, building up extensive vesala networks. Jaguls and Legates are the equivalent of Starfleet admirals, commanding entire Battalions and Orders. 
The Cardassian military is divided into Enlisted ranks, Commissioned ranks and Flag ranks.
Gorrs and Garreshs belong to the Enlisted ranks.
Gils, Glinns, Dalins, Dals and Guls belong to the Commissioned ranks.
Jaguls and Legates belong to the Flag ranks.
To see a comparison between the militaries of the Cardassians', the Romulans' and the Federations', follow the link.
Cardassian Ranks Gorr: Gorr is a Cardassian military rank title, one of the lowest named ranks in use in the 24th century by the Cardassian Guard agency of the Cardassian Central Command. Garresh: Garresh make up the vast bulk of the military. Garresh is a Cardassian enlisted rank title which, in translation to Federation Standard, is approximately equivalent to a non-commissioned officer of comparable military or naval service organizations, such as Starfleet. Gil: Gil (sometimes seen as Kel) is a Cardassian officer rank title which, in translation to Federation Standard, is approximately equivalent to an ensign of comparable military or naval service organizations, such as Starfleet. Gil is either a non-commissioned officer or junior officer rank. Space stations typically carry enough lifeboats only for personnel down to, and including, the rank of Gil. Glinn: Glinn is a Cardassian officer rank title which, in translation to Federation Standard, is approximately equivalent to a lieutenant of comparable military or naval service organizations, such as Starfleet. Glinn is a staff officer rank. Dalin: Dalin is a Cardassian officer rank title which, in translation to Federation Standard, is approximately equivalent to a lieutenant commander of comparable military or naval service organizations, such as Starfleet. The title of dalin was in use in the 24th century by the Cardassian Guard agency of the Cardassian Central Command. Dal: Dal is a Cardassian officer rank title which, in translation to Federation Standard, is approximately equivalent to a commander of comparable military or naval service organizations, such as Starfleet. Gul: Gul is a Cardassian officer rank title which, in translation to Federation Standard, is approximately equivalent to a ship's captain of comparable military or naval service organizations, such as Starfleet. Gul is a command officer rank. Guls hold command ranging in size from vessels to Orders (approx. 500,000 personnel). Jagul: Jagul is a Cardassian flag officer rank title which, in translation to Federation Standard, is approximately equivalent to a commodore or rear admiral of comparable military or naval service organizations, such as Starfleet. Legate: Legate is a 24th century Cardassian officer rank title which is approximately equivalent to an admiral of comparable military or naval service organizations, such as Starfleet. Legate is the highest rank in the Cardassian military, and while it resembles the rank of Admiral in some respects, it is more of a political position than a rank. Since the Cardassian government is a military-controlled stratocracy, Legates serve both military and governmental functions simultaneously.
A more powerful Cardassian ship is the Keldon class starship (which is similar to the Galor-class with more defined aft wings and a large trapezoidal pod atop the main hull). This ship class is assumed to be comparable to the Galaxy-class in tactical capability; why they have not been seen in greater numbers is uncertain. However, the Federation only built a handful of Galaxy-class vessels itself, so perhaps large numbers of the similarly advanced Keldon should not be expected. The Cardassian Obsidian Order kept a fleet of Keldon class starships which were used in conjunction with the Romulan Tal Shiar during the sneak attack in the Omarion Nebula.
The Cardassians have also been known to operate small attack craft such as the Hideki class scout. It is a small attack craft composed of a semi-elliptical fore with a short aft extension ending in a pincer-shaped disruptor weapon. Due to the ship's limited offensive power the Hideki class is confined to border patrol duties during peace time. During the Dominion War the class was present in several major conflicts, they operate in large groups and swarm enemy ships, this allows them to overpower much heavier vessels.
All Cardassian warships seen so far are painted ochre, and have backwards-swept delta winged hulls (resembling an ankh); the delta wings resemble fins, giving the Cardassian ships the appearance of predatory rays.
Cardassian computers utilize data encoded on isolinear rods, in contrast to discs used for similar purposes by human-designed computers.
The Cardassians' homeworld, Cardassia Prime (also known simply as "Cardassia"), is the seventh Class-M planet of its system. The planet's climate is warmer than that preferred by several species—human and Bajoran characters, among others, make comments throughout Star Trek: Deep Space Nine's run about Cardassians' preference for heat, while characters like Elim Garak complain about the uncomfortably cool temperatures preferred by non-Cardassians. Its landscape is often arid, though animal and plantlife are still plentiful on the surface.
The date of first contact between the Cardassians and Starfleet is unknown, but is likely to have occurred mid-to-late 22nd Century, as a Cardassian exile, Iloja of Prim, lived on Vulcan during that time period. Sometime before 2347 the Cardassians attempted to expand into Federation territory and war broke out, lasting around twenty years. Captain Edward Jellico spearheaded successful attempts by Starfleet to negotiate a peace treaty which ended the war.
Shortly after the Cardassians withdrew from Bajor, a Federation presence was established aboard Terok Nor, renamed Deep Space Nine, to assist the Bajoran Provisional Government in rebuilding Bajor. However, the Federation officers discovered a wormhole to the Gamma Quadrant close to the station ("Emissary"). Roughly four months later, the Federation-Cardassian borders were redefined, with the two sides buffered by a demilitarized zone. However, the new border treaty gave Cardassia control of several worlds inhabited by Federation colonists and the Federation colonies inhabited by Cardassians. Disgruntled colonists in the area, feeling that their opinions and wishes had been ignored by both sides, formed a resistance movement known as The Maquis.
In January of 2372 (Stardate 49011) the Klingon Empire attacked the Cardassian Union, believing the Detapa Council of Cardassia (which had just come to power in the wake of the Cardassian Central Command being overthrown, making it the first civilian government of the Cardassian Union with Gul Dukat as military advisor) had been infiltrated by the Dominion ("The Way of the Warrior"). The attack was led by General Martok who, it turned out, had been himself replaced by a shapeshifter, one of the leaders of the Dominion (first revealed in "Apocalypse Rising"; see also "In Purgatory's Shadow").
The Cardassians (as members of the Dominion) captured DS9 ("Call to Arms"), but the Federation managed to block the Bajoran wormhole with self-replicating mines, preventing the Dominion from sending reinforcements from the Gamma Quadrant.
Gul Damar discovered a way to disable the self-replication of the mines and completed the procedure and fired on the minefield seconds before Rom and Kira disabled DS9's weapons in hopes to prevent just that. The USS Defiant attacked DS9 and managed to take it back when the Bajoran Prophets destroyed an entire Dominion fleet, sent to reinforce Dominion lines, on its way through the wormhole. Gul Dukat was captured after his daughter Ziyal was killed by Gul Damar, who was then promoted to Legate ("Sacrifice of Angels").
Under the leadership of Damar, the Cardassian Union, along with the Dominion, continued to gain ground over the Klingon-Federation alliance, and even after Benjamin Sisko and Garak tricked the Romulans into breaking their nonaggression treaty with the Dominion and joining the alliance ("In the Pale Moonlight") they still managed to keep the upper hand.
The revolt started out as just a small legion of troops headed by Damar, but during the final assault on The Dominion over Cardassia Prime by the Federation-Klingon-Romulan alliance, Damar managed to get an open revolt started on Cardassia itself. In response to Cardassian citizens engaging in acts sabotage, the Dominion punished the Cardassians by destroying Lakarian City killing millions of men, women, and children in the process of reducing it to ashes. As a result, the Cardassian fleet switched sides during battle and assisted the alliance, opening a hole in the Dominion lines and forcing the Jem'Hadar and the Breen to establish a new defense perimeter around Cardassia Prime itself. When word of the fleet's defection reached the Dominion command center, the Female Changeling ordered every Cardassian on the planet killed.
With the Cardassian fleet helping the alliance and the rebel's attack on the Dominion headquarters on Cardassia, the Dominion surrendered, ending the Dominion War.
The Cardassian cost due to the Dominion War was the highest of all the major powers. The homeworld was severely damaged by the Dominion, whose Founders ordered a "scorched earth" approach to the Cardassians' homeworld for their betrayal during the final battle of the war. Cardassia was in much worse shape than Bajor and would require years of rebuilding. The long term effect on the ecology of the planet remains to be seen. Over 800 million Cardassians died on Cardassia alone. It remains to be seen if the Cardassian race will be able to recover from this disaster.
In the Voyager episodes "Futures End", Captain Braxton, after having been thrown into the 20th century, describes a police officer as being a "quasi-Cardassian totalitarian". This seems to suggest both that Cardassia and Starfleet are still not on good terms, and also that despite the reforms after the end of the Dominion War, the Cardassia is still a militaristic police state.