Very little is known about the aliens, all that is known however, is that they are connected in some way to the alien mineral "tiberium." A possible name for the aliens is the "scrin." This is based only on the original name for the banshee fighter though which is supposedly created using their technology. The aliens sent the alien mineral tiberium to earth for unknown reasons, possibly to make it habitable for colonisation, possibly to wipe people out from it's damaging effects or any other good reason you can think of. Some sort of what seems to be an alien ship wreckage was present in Command and Conquer (see pic) so there were suggested alien links even before TS. This short paragraph is pretty much all that is known about the aliens. Below is a pic of the banshee fighter and the C&C screenshot. Below that is a screenshot of the Alien Wreckage in TS.