A group of inter dimensional beings made of ice.
"No two ways about it. They were a grave danger. They could have shattered the planet."
-- Brian Kinney (Altar Boy)
Earth is the interface between the Frigians world and the world of their enemy the Thermians. This has led to both groups attacking one another and Earth, for many times. The last known time happened was in Antarctica in July 1997, when both groups were turned away by Honor Guard.
As their name implies they have some sort of abilities or stamina related to colder weather. One member of their attack team was a giant, towering fifty feet race to be giant sized, or it possibly could have been a mechanical creation of some kind.
They used some kind of motorized platforms for maneuvering.