The Babylon Project
Canonbox default.png The following is based on The Mongoose Publishing RPG books and contradicts canon sources.

Thirdspace is a sourcebook for Babylon 5 the Roleplaying Game. It describes the events of the movie Thirdspace as well as the alien horrors of that alternate dimension.


From the back cover...
In 2261 the galaxy was thrown into upheaval in the wake of the last great Shadow War, and the galaxy was caught between ages. It was a time of great change and the responsibilities of the younger races were compounded by the loss of the Ancients. The galaxy – and all within it – was theirs. When a huge and ancient artifact was found drifting in hyperspace by flight crews of the newly neutral Babylon 5, it was brought back to the station to be studied. Bringing the artifact into real space would trigger a chain of events the Vorlons were only able to postpone at their strongest, that would test the tenacity of Captain Sheridan and his crew to the fullest. Through the artifact they found a dimension they called Thirdspace, and the Harbingers it was home to.

This is a sourcebook for the Babylon 5 Roleplaying Game Second Edition that explains in more detail the events that take place in the Babylon 5 telemovie Thirdspace. Such a massive event would send ripples through the galaxy, and this book explains a few of them. Containing rules on how the Thirdspace gate affected Babylon 5 and its occupants, statistics for the deadly Harbingers and the personalities involved, this sourcebook gives readers everything they need to use the events in their own campaigns – if they dare to do so.


This sourcebook details the Thirdspace Event as it happened in the Babylon 5 movie Thirdspace along with a detailed account on the aliens of that alternate real who are known as the Harbingers. The factbook provides the background of the Harbingers, their impact on galactic history in the time of the First Ones as well as the Harbinger Cults that follow them. In addition to this, a list of technology is provided that is used by the aliens.

Furthermore, the sourcebook provides a detail account on the many mistakes of the First Ones; covering the Mindriders, Shadows, Triad, Walkers, The Hand and the Vorlons.



  • Hand
  • Harbingers
  • Kirishiac
  • Lliestans
  • Mindriders
  • Ralgans
  • Ru Ha'rus
  • Shadows
  • Shierren
  • Soul Hunters
  • Speakers
  • Torvalus
  • Travelers
  • Triad
  • Vorlons
  • Walkers

Vehicles & Ships[]


  • Cherubim Invasion Frigates
  • Nephilim Destroyer
  • Seraphim Dreadnaught
  • Throne Gateship


  • Lordship


  • Thoughtforce


  • Dark Knife


  • The Traveller of Sigma 957


  • Triumviron

Weapons & Technology[]


  • The Thirdspace Aliens are given the name Harbingers in this sourcebook.