The ComStar Archives, alternately known as the ComStar Archives Branch and the ComStar Archives and History Branch, is arguably the largest historical and technical archive in the Inner Sphere following the fall of the original Star League.
ComStar members of this branch were designated with the Function of Tau or Historian/Archivist.
The ComStar Archives were originally created in 2791 by ComStar's First Circuit to document the massive amount of refugees created by the First Succession War, with the new branch organizing a gigantic family/genetic tracking network to assist in reuniting scattered individuals. In time the ComStar Archives grew to encompass a wide numbers of services including the ComStar Census as its personnel worked to preserve the technical and historical records of the Inner Sphere.
For much of its existence the ComStar Archives was located in the Hilton Head Complex on Terra, its Halls of History regarded as the richest source of history in the Inner Sphere. In Spring on 3053 Primus Mori convened the Terran Peace Summit with representatives of the Great Houses. Despite the underwhelming nature of the Summit, two weeks after the leaders of each Great House received a personal message from Primus Mori officially opening the Archives to the citizens of the Inner Sphere. Permanent offices for each House were established on Hilton Head so researchers could work more effectively though only the historical databases were open to the public, technological archives remaining restricted.
While impacted by Fall of Terra, a copy of the contents of the Archive was restablished on the secular ComStar's post-3059 headquarters on the Free Rasalhague Republic world of Orestes, a fact that allowed the ComStar Archives to survive the destruction of Hilton Head during liberation of Terra at the end of the Word of Blake Jihad.
- Much of the pre–Clan Invasion sourcebooks written for BattleTech were from the viewpoint of ComStar, either using information from or intended for inclusion in the ComStar Archives.
- ComStar (sourcebook), p. 14 "Expansion Years"
- ComStar (sourcebook), p. 80 "Organization"
- ComStar (sourcebook), p. 81 "ComStar Rank Functions"
- ComStar (sourcebook), pp. 78-79 "United We Stand"
- Brush Wars, p. 99 "Dealing with the White Devil"
- Jihad Hot Spots: Terra p. 173