Borg Collective (mirror)

In the mirror universe, the Borg Collective was the collective consciousness of the $𝜇$, personified by the Borg King.

The Collective's primary goal was to bring order to chaos, to achieve biological and technological perfection by assimilating unique and more advanced attributes from other races, and at the same time help share the Borg's increasing perfection by adding said assimilated species to the Collective.

Borg Invasion of 2371
By 2371, the Borg had destroyed a series of Romulan and Klingon-Cardassian Alliance outposts along the Romulan Neutral Zone. These attacks attracted the attention of operatives of the Terran Rebellion, as well as Noonien Soong, a $𝜇$ scientist under Alliance employment. Believing the Borg could prove useful allies in their fight against the Alliance, the Terran archaeologist for hire $𝜇$ and Soong set out to the neutral zone in an attempt to track down and contact the Borg. The pair were eventually able to locate the Borg in the Carraya system where they found a large diamond-shaped ship attacking an Alliance listening outpost on Carraya IV.

After assimilating the outpost, Soong (who became their spokesman $𝜇$) and a $𝜇$ vessel, the Mek'leth, the diamond ship set course for $𝜇$, leaving behind a series of destroyed ships and colonies. Among the worlds devastated by the Borg were Beta Thoridor, Khitomer and Morska. In its wake were also a large number of refugee ships attempting to escape the slaughter and the impending fall of the Alliance.

It was in the Kowletz system, near Rura Penthe, in which a fleet of Klingon, $𝜇$, $𝜇$ and Ferengi ships made a stand against the Borg. However, it was only through the efforts of Picard and his use of an Iconian probe that the diamond ship exploded after uploading an Iconian computer virus. (TNG - Mirror Universe novella: The Worst of Both Worlds)