Horos was a heavenly body situated within the Horos system. This system was within the Lambda sector, which itself was part of the Slice region of the Mid Rim. The planet shared a moniker with the hyperlane called the Horos Spine. During the Andoan Wars—a conflict that spanned from 57 BBY to 39 BBY between the Spiverelda, a collection of worlds that had been colonized by the Aqualish species and were under the sway of Ando, the Aqualish homeworld, and the fifteen planets settled by the Aqualish referred to as the Andoan Free Colonies—the Spiverelda's military triumphed over the Free Colonies' forces during a battle that took place at Horos.
The reference book The Essential Guide to Warfare, published in 2012 and written by Jason Fry and Paul R. Urquhart, introduced Horos to the lore. The Essential Atlas, a reference released in 2009, located the Horos system, and consequently Horos itself, in the Q-15 grid square.