Tall, long-necked, humanoid in appearance, marked by several bony protrusions and ridges: one from the shoulder to under the ears, whose bottom lobes in turn are more pronounced forward to the jawline, and from above the eyes and back over the head to the rear base of the skull, showing through hair. Other ridges run from the nose line to the forehead, and along the chin to define a sharp jawline. Their skin type and hair vary from light purple to a greenish hue and near black. Predatory in large numbers, more cautious alone and instinctively searching out a dominant position in any social setting. Children may keep pets. Women as well as men are allowed to be Gul in ship command.
The occupiers of Bajor subjugated the people and mined its resources, annexing it outright some 19 years into its 60-year occupation (beginning 2309) and building Terek Nor, now known as Deep Space Nine, initially as a mining station in 235, perhaps using Romulan technology in some components. They then stripped the surface of Bajor and Deep Space Nine alike in vengeance when they withdrew less than two weeks before stardate 46388, leaving everything from basic systems to religious areas in shambles. Some who resisted, including four Promenade merchants, were killed.
The Cardassians also stole eight of the nine Bajoran prophets' orbs, causing a worried Kai Opaka to charge Commander Sisko with locating their Celestial Temple before the Cardassians found and destroyed it. Despite that, as a show of faith, Commander Sisko allows Dukat's crew aboard for shore leave. Their reputation for maltreatment of prisoners is well known, but in the world of commerce they are known for paying their bills. Their officials and officers were not above taking bribes from lowly Bajorans.
Other cultures don't seem to share their taste in food, such as yamok sauce.
Their engineering standards tend to be lower than Starfleet specifications. Deep Space Nine's fusion powerplant design considers a range of 20% in operating efficiency to be within normal. Cardassian genetic engineers are advanced enough to be well-known by their trademark use of monoclonal links in their DNA-building; whether by open exchange, captured record or espionage, the details are easily researched in Federation records.
They may have compulsory military service, at least for males. Death services are called "funerals" and they can be public occurrences, especially for major leaders. Military monuments line the planet, with some serving as burial sites.
One of their greatest characteristics is devotion to family; caring for parents as well as children. Families of up to four generations under one roof are not uncommon. Swearing the truth on the lives of one's children is tantamount to the highest honesty a Cardassian can attest to — as Dukat does to Commander Sisko. Parents are manipulated by state media in the name of their children, and the presumed-guilty justice system aims to impress children against anti-state lawlessness and chaos, inviting some to the courtroom live and others to watch. The revelation that he abandoned a child on Bajor, even one thought dead, is enough to publicly and privately humiliate a politician like Pa'Dar, ruining his career. Despite that, true orphans have no status in society and are simply forgotten.
Another trait is an attention to detail. They taught record-keeping skills to many planets, including Bajor. Cardassians are famous for their photographic memories. When alleged that children at age 4 are put into intensive mind-training programs, it is acknowledged as the "unparalleled" educational system of the quadrant. Education is power and joy is vulnerability, Dukat asserts in Orwellian-like tones. The mental training can extend to enough discipline to deflect a Vulcan Mind Meld. Kovat says one old native saying is, "Confession is good for the soul."
Their physiology and constitution is much stouter than the human norm, or at least Garak's is. Showing immunity to the effects of depressants and anesthetics, neither two-plus bottles of Kanar nor 30cc's of Triptacederine had any effect on the Cardassian. The latter amount would knock out an Algorian Mammoth.
Similar to Humans, Cardassians celebrate birthdays, respect marriage, and use a given name before the family name. Cardassians also respect advanced age as a sign of power and dignity.
It was recently determined that Bajorans made interstellar contact with Cardassians before they had the capability of spaceflight.