Horse Head Nebula
Location:	Nineteen Pillars of Ascension / Milky Way Galaxy Bastion Space/ Milky Way Galaxy Flarunium Realm / Milky Way Galaxy Council space / Milky Way Galaxy Alliance space / Milky Way Galaxy Coalition space / Milky Way Galaxy Dominion space / Milky Way Galaxy
System(s):	Pax Fortuna Irisa Strennus
Relay(s):	Pax Relay
Population:	100,400
Species:	Prothean Asari Salarian Turian Human Hanar Drell Elcor Volus Batarian Quarian Krogan
Affiliation:	Prothean Empire United Citadel Council of Species Systems Alliance New United Galactic Front of Races Systems Coalition Galactic Dominion Unified Galactic Republics
Tier:	Tier VIII
Capital:	Noveria

The Horse Head Nebula, alternatively spelt Horsehead Nebula, is a cluster located near the northwestern edge of Alliance space, an autonomous region of the Systems Alliance, and formerly the location for the headquarters of Cerberus. The Horse Head Nebula was settled by the Citadel Council very early on in its existence, being discovered by the first asari-salarian explorers by 429 CE, and fully developed by 386 CE. The cluster was exchanged several times throughout the course of the Krogan Rebellions between both sides, until a decisive engagement during the Noverian campaign where the Turian Hierarchy finally recaptured the cluster. However, Noveria's belligerence towards the Council would lead to the Council relinquishing direct control of the cluster, instead delegating it to indirect rule due to Noveria's insistence on skirting the law. This put them in trouble during the First Spectre War, when the renegade spectre Kaaysha T'vevo proclaimed herself sovereign of Noveria: despite the Council "liberating" the planet from T'vevo's rule, the Horse Head Nebula still insisted on autonomy, which made it an all too tempting base for Terminus and Attican pirates and criminal gangs to launch raids into Council space with impunity. And by 2158 CE, it had become the home of Cerberus, and the center of their operations.

After the Reaper War, Noveria demanded the Systems Coalition forces in the region to leave, but the Coalition, seeing a chance to remove a thorn in their side, ignored their demands and remained. Unable to force the issue, Noveria slowly ceded its autonomy to the Coalition, until it eventually surrendered to full Coalition governance. Since then, the Horse Head Nebula has remained a part of the Coalition, despite a failed Noverian attempt to take advantage of the Dominion Civil War and declare independence.

The cluster is named for the shape of the nebula, which is said to look like a horse's head.