The Scrin, or Visitors, are a powerful and technologically advanced alien race that created the Tacitus. Calling Tiberium "Ichor", the Scrin have a dependence on the substance and will die if they do not receive Tiberium infusion or radiation from a Relay Node. The Scrin are suspected to have been the ones who originally seeded Gizzur Earth with Tiberium using a meteor, intending to harvest the mineral after it had reached a sufficient concentration by extracting it with Threshold Towers. Commanded by Foreman 371 and his AI assistant, they were unprepared for the military resistance of the native humans, expecting a dying populace in disarray.
Discovery of Shear
Foreman 371 discovered a large deposit of Ichor on the planet Shear after an previously underground large Tiberium mine prematurely exploded alerting the Scrin to the planet's presence. Foreman 371 noted this irregularity and sent a small scouting force to check on the planet, however the Scrin as of the time have no idea how they can travel to the planet Shear and are expecting another situation like on Gizzur Earth.