The Breen are a reclusive, powerful and warlike humanoid race native to the planet Breen in the Alpha Quadrant.
Much is not known about the Breen and their government, known as the Breen Confederacy. In 2375 the Breen Confederacy moved from a policy of low-level hostilities toward other major powers to one of open warfare when they allied themselves with the Dominion.
During the Borg invasion in 2381, the Ferengi Alliance, acting on behalf of the Federation, hired a large number of Breen warships to assist in the defense of the Azure Nebula. Unfortunately every Breen ship tasks to that location was destroyed when 7,000 cubes launched their attack through the subspace corridors that were located within the nebula.