Breenscience fiction franchise Star Trek. They wear suits which generate an arctic environent inside them; this is because their homeworld is believed to be an arctic wasteland. They have never been seen on the show outside their suits (although a few characters on the show have seen them offscreen). They established the isolated Breen Confederacy in the Alpha Quadrant and became a powerful ally of the Dominion of the Gamma Quadrant.
Not only is their appearance mysterious, but their behaviour perplex others as well. The Romulans have a saying: "Never turn your back on a Breen." This is shown when a Breen grabbed a pistol from the holster of a Jem'Hadar soldier whose back was turned to him in a Dominion asteroid prison.
The Breen suits are usually thought of as refrigeration suits, but some speculate that the Confederacy is a comfortable environment (from the Cardassian point of view). The helmet of the suit consist of a glowing green visual piece and a beak, which seems to suggest the breen have an unusual facial structure. The Breen have no blood or any similar liquid circulatory system. The Breen costume, especially the helmet, looks very similar to the one worn by Princess Leia when trying to infiltrate Jabba the Hutt's palace.
The Breen eat algae paste, which is probably the only plant life that grows in an arctic environment.
Even though their language is entirely electronically coded and then broadcasted outside of the suit, they still can be translated with ease by the Dominion. The leading representative of the Confederacy to the Dominion is the Thot (similar in rank to a General).
Although the Breen appear almost exclusively in episodes of , one Breen appeared as a hologram enhanced by the Hirogen in .