Star Trek: Deep Space Nine is one of the most unique entries the franchise has ever produced. After two live-action series and an animated series all set on starships, this series moved the setting to a space station. Without the exciting new destinations in each episode, the show's writers had to ensure the characters who came across the space station were complex. That, in turn, led to some great characters who only ever appeared on the show once.
These characters made the most of their limited screen time, providing character growth to series regulars, advancing key storylines, and bringing joy to fans of this compelling series.
10 Kang
Kang is one of the legacy characters to make his way aboard Deep Space Nine. He first appeared as an antagonist of Captain Kirk in Star Trek: The Original Series before making his return in Deep Space Nine. He appeared in episode 19 of season two, entitled Blood Oath. He is on a mission to resolve a blood feud before he dies.
Throughout the episode, his work with Jadzia Dax leads him to recognize her on the same level as the other Klingons he served with. It also provided an amazing social commentary in the same vein that Gene Roddenberry originally envisioned where bonds were allowed to extend beyond blood, race, or species.
9 Vreenak
Senator Vreenak was incredibly important to the Dominion War storyline as well as the development of Captain Benjamin Sisko's character. He appeared in episode 19 of season six, entitled In the Pale Moonlight. Vreenak is an important part of the plan hatched by Sisko and Garak to cause the Romulans to enter the Dominion War.
Vreenak is able to see through Sisko's deception and refuses to allow the space station commander to manipulate him. He would die in a shuttle accident set up by Garak which would lead to the Romulans entering the war as Sisko and Garak had planned. Vreenak's appearance leads to a change in Sisko's moral code, and his unknowing sacrifice ends up saving Deep Space 9.
8 Ee'char
Ee'char served as a cellmate for Miles O'Brien in an implanted memory where O'Brien thought he was serving a 20-year prison sentence. He appeared in episode 19 of season four, entitled Hard Time. Ee'char seems very helpful but is unwilling to help O'Brien escape what he thinks is a prison cell. Eventually, the perceived bond between O'Brien and Ee'char is broken and O'Brien kills Ee'char for a piece of food.
When O'Brien is back on the space station, the guilt over killing Ee'char in the memory has him on the brink of suicide. Ee-char serves as an amazing reminder of the effect incarceration can have on a person's mental well-being.
7 Lenara Kahn
Lenara Kahn's appearance led to some interesting questions for what may be the most controversial episode of Star Trek ever. She appeared in episode six of season four, entitled Rejoined. In the episode, the trill that is linked to Jadzia Dax meets up with the trill linked to Lenara Kahn. The two were an item when linked to previous hosts but are now linked to new hosts. The episode raises questions about love and cultural respect as the pair are not supposed to be together with their new hosts, but they still feel a bond with one another.
The trills have to consider throwing away everything they've worked for to be together or if one of them can walk away from the other. The appearance also broke boundaries as the two actresses playing Kahn and Dax shared a kiss, the first kiss between two female characters on any Star Trek series.
6 Adult Jake Sisko
While Jake Sisko may be a regular character, the adult version of him from another timeline only appeared on the show once. He appeared in episode three of season four, entitled The Visitor. In the episode, Captain Sisko is believed to be dead after he ends up in a temporal displacement where no time passes for him but does everyone else. Adult Jake Sisko is a published author, but upon learning his father isn't dead, the adult version of Jake works to restore his father.
He accomplishes this feat by sacrificing his own future so Captain Sisko can return to his own time and further improve his relationship with Jake in the current timeline. It's a powerful episode about the desire for more time with lost loved ones and the lengths some are willing to go to achieve that.
5 Aamin Marritza
Aamin Marritza's appearance serves as an incredible social commentary on the future and how it may not be as enlightened as we would want it to be. He appears in episode nine of season, one entitled Duet. Marritza is a Cardassian arrested on the station for his alleged role in a massacre at a labor camp. He is believed to be the Cardassian who operated the camp and committed the atrocities before it is revealed that he was just a filing clerk at the camp and is living with survivor's guilt for the atrocities he witnessed.
In just one appearance, he is able to make the viewer hate him with every fiber of their being when they think he is a war criminal. Then, he is able to garner compassion from the same viewers when his survivor's guilt is made known.
4 James Leyton
What happens when fear and paranoia take over leaders? Usually, a police state and that's what we get with Admiral James Leyton after the Dominion is successful in sowing distrust. He appears in episode 12 of season four, entitled Paradise Lost. Leyton's fear and paranoia of the shapeshifters who lead the Dominion led him to declare martial law and to start testing people's blood to see who is an imposter.
It's an overreach in government that is increasingly frightening because it's a very believable route. It's been seen throughout history and unfortunately will continue as long as those in charge promise safety in exchange for freedom.
3 Kira Meru
Kira Nerys gets to meet her late mother and learns she wasn't the woman Nerys thought she was but was still strong in her own way. Kira Meru appears in episode 17 of season six, entitled Wrongs Darker Than Death And Night. Kira Nerys always viewed her mother as a fighter but learns Kira Meru's strength came from her willingness to stay with Dukat and the Cardassians to provide for her husband and daughter.
The episode tackles the intricacies of war and how things aren't always black and white. This vision of the past leads Nerys to view her mother as a collaborator in what she sees as an unjust occupation but ends with her being unable to condemn her own mother.
2 Cal Hudson
This Starfleet officer comes in to help deal with the Maquis situation, a group of colonists displaced by the Federation's treaty with Cardassia. Cal Hudson appears in episodes 20 and 21 of season two, entitled The Maquis: Parts One and Two. He's an old friend of Captain Sisko's who, at first, appears to be helping the Federation deal with the Maquis, who they must treat as enemies due to diplomatic relations.
But he reveals himself to be helping the Maquis, willing to throw away everything to help the little guys while questioning the values of the Federation that failed them.
1 Eris
Eris paves the way for the primary villains of the entire series. She appears in episode 26 of season two, the Jem'Hadar. She's an alien with psychic powers who is in the company of Sisko and Quark after they've been abducted during a camping trip.
After working with Eris to escape, she reveals herself to be a Vorta, a lieutenant in the Dominion. Eris tricks Sisko and Quark the entire time and sets up the Dominion on its quest to retaliate against the rest of the galaxy for what it views as past wrongs.