Regular Cast
 
 
 

 Avery Brooks as Captain Benjamin Sisko

Originally from New Orleans, the son of a Chef, Benjamin Sisko attended Starfleet Academy in San Francisco. He rose rapidly through the ranks and was a Commander on the USS Saratoga when it was destroyed by the Borg during the attack at Wolf 359. His wife, Jennifer was killed during the attack and he was left to bring up his son, Jake, by himself. For three years after the Borg attack, Sisko was a broken man, never being able to recover from the shattering loss of his wife.

During this time, he worked at the Utopia Planitia shipyards working on various projects including the prototype of the anti-Borg gunship (the USS Defiant). He was reassigned to Deep Space Nine as it's commander when the Cardassians pulled out of their occupation of Bajor. When he negotiated an understanding with some lifeforms who live outside time allowing the use of the Wormhole in Bajoran space, he became an important figure in Bajoran religon, The Emissary.

For the first two seasons, he commanded DS9 with the rank of Commander, but in season three he was promoted to Captain.
 
 
 
 

 Rene Auberjonois as Odo

Odo was discovered floating in the Deanorious Belt near Bajor and taken back to a research institute in occupied Bajor. After many years as a subject of study, he became the head of security on Deep Space Nine when the Cardassians needed an impartial being to investigate a spate of murders. He remained on the station when it came under Federation control, and used the position to allow him to continue to explore his origins. It became apparent that his people came from the Gamma quadrant and through several clues he eventually found his way home, only to discover that his people did not share his belief in justice and freedom for all.
 
 
 
 
 

 Siddig El Fadil as Dr. Julian Bashir

A hotshot medical student sent to Deep Space Nine fresh out of Starfleet academy medical school, is initially rather unpopular with the rest of the crew. His has a major chip on his shoulder about not being the best in his class. While on Deep Space Nine, he's had an opportunity to do some basic research and has become quite an expert on treating a wide range of alien species.

Siddig El Fadil changed his "Stage Name" to Alexander Siddig and the openning credits were changed to reflect this from the start of season four. Presumably, Hollywood found "El Fadil" too complicated for them?
 
 
 
 

 Terry Farrell as Lieutenant Commander Jadzia Dax

The biography of Jadzia Dax has to take two parts; that about the symbiot "Dax" who is around 300 years old and has had a number of hosts over the years, and that of the humanoid Trill woman, Jadzia. The symbiot has a colourful history, having been joined to no less than seven other hosts including a murderer. The host before Jadzia was Curzon Dax, a great mentor of Benjamin Sisko in his youth.

Jadzia was an attractive and brilliant young woman who worked very had to get accepted for the Trill joining programme. She was thrown out of the programme after a poor report from Curzon Dax during the initiate assesment. She was then reaccepted into the programme in an unprecidented move and finally became the host to Dax when Curzon died.
 
 
 
 

 Michael Dorn as Lieutenant Commander Worf

Worf is the son of Mogh and he was born on the Klingon Homeworld. His natural parents died in a Romulan attack at the Khitomer outpost soon after the alliance between the Federation and the Klingon empire was formed. Then he was adopted by Sergey and Helena Rozhenko. Sergey was one of the Federation's rescue team that arrived at the outpost after the Romulan attack. Worf graduated from the Academy and was the first Klingon to enter Starfleet. Worf was assigned as flight control officer on board the U.S.S. Enterprise. He was promoted to Chief of Security when Tasha Yar was killed. Later, when it was discovered that the outpost was betrayed, apparently by Mogh. Under Klingon law, Worf had to carry the dishonor of his father. However, Worf learns that the real traitor was the head of the powerful Duras clan. Eventually, his honour is restored.

Worf has a younger brother, Kurn, and a foster brother, Nikolai. He also has a son, Alexander, from his mate K'Ehleyr (a half-human, half-Klingon female who was later murdered by Duras) and a bonded son, Jeremy Aster.

At the start of season four of DS9, Worf is assigned to DS9 (transferring from Security to Command in the process) when the Klingon-Federation alliance breaks down. Worf sides with the Federation, and so Gowron declares him a traitor to the Empire once more.

In season seven, in the midst of the federation-dominion war, and the new klingon-federation treaty, worf is valued yet again by the empire. He is respected by the klingon empire's High General, who takes him under his custody, making worf his brother. This move vanishes all of worf's dishonor from his father, "...what is past is past!".
 
 
 
 
 

 Cirroc Lofton as Jake Sisko

Jake is Captain Benjamin Sisko's son. He doesn't very much remember life on Earth since he has been aboard four different starships and stationed on two planets during his father's career. This transient life style has taught him how to scope out a new terrain and assimilate quickly. At the same time he has an inner fear of forming new friendships because he loses them so easily. He dreams of going to live on Earth.

He collects holodeck programs of various places on Earth that he uses to try to fulfill his fantasy. Deep inside he knows that his mom would still be alive if his family didn't live in space, and he has a suppressed bitterness about it. When they arrived on DS9, his father promised there would be other kids on the station. As it turns out, there are only a handful of various alien species. Only one is his age, Nog, a Ferengi teenage boy who was considered bad influence for a time by his father. Besides that, he is close with his dad. For a time O'Brien tried to teach Jake about DS9's engineering systems, but now Jake wants to become a writer.
 
 
 
 
 

 Colm Meaney as Chief Operations Officer Miles O'Brien

Miles Edward O'Brien was born on Earth in Ireland. He has a unique talent for all things mechanical and so studied advanced engineering at the Academy. He has served on the USS Rutledge with Captain Benjamin Maxwell as tactical officer. He never forgot the encounter they had on Setlik III with the Cardassians. It left him skaken and gave him a deep hatred for the Cardassians for what they did, and that he had to kill to defend the survivers. After the Setlik III massacre, he was reassigned to the Enterprise. First, he served as Bridge Conn, then he was promoted to Transporter Chief and he became a transporter specialist.

When Miles was on board the Enterprise, he married Keiko Ishikawa (introduced to him by Lt Cmdr Data) and they had a daughter, Molly (delivered by Worf!). Finally, he was assigned to Deep Space 9 as Chief Operations Officer.
 
 
 
 
 

 Armin Shimerman as Quark

Quark is the Ferengi bartender on DS9. The Ferengi race, has seen in The Next Generation, are ugly, sexist, greedy little aliens who are interested only in profit and getting theirs hands on anything of yours they happen to fancy. Quark runs many of the entertainment concessions on DS9. He has a bar, a restaurant, a gambling house (dabo), and the holosuites upstairs where your every fantasy can be played out. He spends most of his time behind the bar. If there is some scam being run in the sector it often involves him. But beyond that, he is a charming host, in a Ferengi sort of way. He forges interesting relationships with Captain Sisko and Constable Odo. He lends a hand to dissolve problems as long as there's something in it for him. His completely sexist attitude makes Kira an obvious adversary and he is consumed with passion for Dax.
 
 
 
 
 

 Nana Visitor as Major Kira Nerys

Major Kira Nerys is a former member of the Bajoran underground. She is now an outspoken critic of the provisional government of Bajor. Having fought for freedom all her life against the Cardassians when they invaded Bajor, it has angered her to see the older leaders throw it all away through their petty dissensions. She has been trying without success to reach the Kai (spiritual leader of Bajor) herself to air her grievances.

So it is very possible she was sent by the government to be the Bajoran administrator at the space station simply to get her outspoken voice out of earshot. Kira loathes the Cardassians and she committed atrocities against them in the name of freedom, some of which bother her. But others in the Bajoran underground begin a new wave of terrorism and she is forced into a moral quandary about tracking them down and bringing them to justice. Some of them consider her a turncoat.