The Centauri Republic
The Centauri Republic is a once great but currently declining power in the Babylon 5 universe.
Biology
Superficially, the Centauri appear so similar to Humans that when the two species first encountered each other, the Centauri tried to claim that Earth was a lost Centauri colony. In truth, there are significant differences between Centauri and Human anatomy.
The Centauri have two hearts. The larger heart is the primary blood-pumping organ, while the smaller heart purifies the blood in addition to providing additional pumping power.
The Centauri have six duplicated sex organs. The male organs are prehensile tentacles that can grow as long as one and a half meters. The female organs are slits on the lower back, three on each side of the spine. Sexual intercourse can take place utilizing just a single tentacle and slit, but increasing the number or penetrations up to six increases the sexual pleasure.
Like most other races, the Centauri have telepaths. Many mundane Centauri also have a talent for prophecy. The majority of these people merely experience a surprisingly accurate prophecy of their own death in a dream. However, a select few of them - all women - can foretell the futures of those who consult them. These Prophetesses are highly revered in Centauri society.
Culture
The Centauri have a highly aristocratic society. The Noble Houses control all power and wealth. The only way a man of lesser birth can achieve any status in Centauri society is through exemplary success in the military or by obtaining the favor of a noble.
At all levels of Centauri society, the women are blocked from positions of power. Women are not allowed to hold important offices, and often they neither work nor receive an advanced education. Those few women who do achieve power usually do so by manipulating others from behind the scenes.
The Centauri hold family and honor in high regard. Parents or the Heads of Houses often arrange marriages to cement alliances with other families.
Centauri men are ostentatious. They wear their hair in a peacock fan. The higher their station, the higher they style their hair. Women, on the other hand, most often shave their heads with the exception of a single ponytail.
The Centauri are a culture on the decline. They have fallen far in the past several hundred years. The size of their empire has shrunk, and their military is smaller than it was during their time of expansion. Many Centauri wallow in nostalgia, longing for the days of glory as they substitute decadence for accomplishments. They pretend to be what they once were rather than what they are. Others are bitter and resentful at the position of their Republic.
Religion
The Centauri worship the Great Maker, a monotheistic deity, plus a large pantheon of nearly fifty other gods. Some of their gods include Ilarus, the goddess of luck; Li, the goddess of passion; Morgoth, god of the underworld and protector of front doors; and Venzen, god of food. Several ancient emperors have also been elevated to godhood.
While the Vorlons apparently visited Centauri Prime in the distant past and genetically engineered telepaths, it is not clear whether they also arranged for favorable attitudes toward their angelic appearance. When Vorlon Ambassador Kosh revealed himself on Babylon 5, Centauri Ambassador Londo Mollari saw nothing. It is not clear whether the Vorlon telepathic projection had no effect on any Centauri or if only Mollari was unaffected.
Technology
Centauri technology is second only to the Minbari among the younger races. However, the Centauri never challenged the Minbari in earlier years of space travel, so it is difficult to say which side would have been victorious in a conflict.
The Centauri have shared much of their technology with the Earth Alliance. Also, most Narn technology is developed from equipment the Centauri left behind when they abandoned their occupation.
Government
The Centarum and the Emperor rule the Centauri Republic. The power of the Imperial Throne has varied over the years based on the personality of the Emperor and the makeup of the Centarum. Some Emperors have been mere figureheads while others have been dictators.
The Noble Houses control the Centarum. Each House controls a seat, and it is passed to the House's heir when the holder dies.
The bureaucracy holds much of the real power of the Centauri Republic. The various Ministers, appointed by the Emperor and approved by the Centarum, control the day-to-day operations of the government. Each Minister controls what information he releases and what advice he takes.
True Centauri politics take place behind the scenes in backroom deals. Blackmail is a tool that is often used. Each House has a set of blackmail documents about the other Houses known as Purple Files that they use to secure cooperation when necessary.
The political power of the head of a House can rise and fall as his accomplishments and alliances with other Houses change. Centauri policy can change quickly as the result of a particular House gaining or losing influence in the Centarum or Imperial Court.
Relations with Other Species
While the Vorlons are likely responsible for the genetic engineering of Centauri telepaths, they may not have arranged for the Centauri to be predisposed to their angelic images. The Vorlons considered the Centauri to be a dying people who should be allowed to pass.
The Shadows allied themselves with the Centauri Republic in 2258 as they prepared for the next Shadow War. At first they merely performed military actions as favors for Ambassador Mollari. Soon they took a more active part in the "alliance", calling in military favors from the Centauri in exchange for their help and dictating the division of conquered territories. They bypassed Ambassador Mollari in favor of Lord Refa, and eventually they made personal contact with Emperor Cartagia himself. Emperor Cartagia allowed them to have a base on the Island of Selene in exchange for the promise of godhood. After Cartagia's assassination, Mollari blew up the Island of Selene, destroying all the Shadow forces there, and killed Mr. Morden. He hoped this would permanently sever their relationship with the Shadows.
The Narn Regime is a hated enemy of the Centauri Republic. The Centauri occupied Narn for most of the 22nd Century when they brutally savaged its environment and people. Their second occupation in 2259 through 2261 was preceded by an attack with illegal mass drivers. In 2262, a Narn fleet exacted revenge by bombing Centauri Prime from space.
The Centauri Republic has always been smart enough to treat the Minbari with respect and not get involved in hostilities with them.
The Centauri Republic has a great affinity with the Earth Alliance. The Centauri were the first aliens that Humans encountered. The Centauri quickly opened diplomatic relations after first contact in 2156 and began trade. While the Centauri passed on much of their technology to the Humans and leased the use of their jumpgates, they were most interested in artifacts of Human culture in exchange. The Centauri Republic allied with the Earth Alliance in 2259, but this wasn't surprising since both governments were being influenced by the Shadows.
After the neutralization of the Narn, the Centauri attacked several members of the League of Non-Aligned Worlds in order to secure their borders. In more peaceful times, cooperation between the Centauri and Narn inspired the Non-Aligned Worlds to adopt certain policies like the formation of the Interstellar Alliance.
After the Shadows went Beyond the Rim and Z'ha'dum was destroyed, the homeless Drakh secretly invaded Centauri Prime. They implanted the Regent and later Emperor Mollari with keepers to monitor and control their actions. They equipped a large portion of the Centauri fleet with Shadow devices designed to automatically control the ships. They sent these vessels out to prey on Alliance shipping. When the Centauri aggression was discovered, war erupted between the Centauri Republic and the Interstellar Alliance. This was all part of a plan to isolate the Centauri. Over the next several years, the Drakh carefully cultivated isolationist and xenophobic attitudes among the Centauri while building a huge Centauri fleet intended to attack the ISA. The Drakh fled Centauri Prime after Vir Cotto exposed them.