A race who believe in balance with the forces of nature and advancement.
- Martial Pacifist: They only fight for survival. Their only enemies are the Breen (who kidnap them as slaves and steal their crap) and the Borg (who are everyone's enemy).
- Morality Pet: To J'mpok's Klingon Empire, who view them as very honorable for saving a Klingon Fleet decades ago. The Klingons don't even want to conquer them.
- Ambadassador: Subverted, he doesn't want to fight anyone. At the Borg conference he states that the Deferi will remain neutral if a consensus can't be reached.
- Big Good: For the Breen Arc.
- Early-Bird Cameo: He's involved in a minor and optional diplomatic mission on Starbase 39. He's very important later in the game.
- Not-So-Omniscient Council of Bickering: Surah has a massive case of packing up his bags and going home whenever things aren't "in balance". He does this in a side mission at Starbase 39 and does it again during "Second Wave".
A race of humanoids who wear environmental suits and wield cryogenic weapons.
- Blue and Orange Morality: They have a warrior code like the Klingons but prefer to take prisoners as slave labor. Large-scale massacres are offensive to them, though.
- Evil Is Deathly Cold: They use ice as a weapon against other races.
- Even Evil Has Standards: The Breen are bad guys, as a general rule, but even they are disgusted by Thot Trel's actions.
- Gas Mask Mooks: The Breen invoke this, even if it's more like humans in refrigerators.
- Malevolent Masked Men: They wear environmental suits that make them look scary.
- Slavery Is a Special Kind of Evil: We see one of their slave mines as a way to emphasize what enormous jerks they are.
- Social Darwinism: Their code of honor is based on survival of the fittest. Needless cruelty is offensive to most Breen but they'll do anything if it serves a purpose.
- The Unintelligible: As per their depiction in Deep Space 9, the Breen still speak in a series of metallic, electronic sounds, though the text subtitles still shows what they're saying; most of the time it's typical Evil Gloating.
- Big Bad: Of the Deferi arc.
- Dramatic Irony: Believes the Preserver Archive will contain innumerable weapons to help the Breen dominate the galaxy. It's a stasis chamber containing Preservers.
- Evil Overlord: Acts like this as he commits numerous war crimes, gloats, takes slaves, and generally acts like a monster.
- Kick the Dog: He does this numerous times to the Deferi. So much so his own men are disgusted with them.
- Large Ham: In the tradition of Hakeev and several other characters.
- Last Words: Signify what kind of ego the man has."But I'm Thot Trel..."
- Villainous Breakdown: Has one after the discovery of the Preserver Archives' true contents. People. His career is effectively over as he's conducted a war for something his superiors will deem worthless.
- 0% Approval Rating: The Breen under his command are deeply uncomfortable with his war crimes.
- Benevolent Precursors: All life in the galaxy is descended from their efforts.
- Big Good: They have the potential to be this for the entire galaxy. They die before it can happen.
- Disappointed in You: Their reaction to the Iconians' decision to kill them all.
- Earth-Shattering Kaboom: The Iconians deliver one of these to their world.
- Human Popsicle: The Preservers are all on ice at the start of the adventure. They die before many are awoken.
- The Omniscient: Every Preserver has the entire collected sum of their race's knowledge in their head.
- Sealed Good in a Can: They're a race that has the potential to change the whole of galactic history. Too bad they don't get the chance.
- Shoot the Shaggy Dog: They waited millions of years to meet their children and ended up being killed by their Firstborn.