"we are the means to your salvation, we are the means to your death! we are the Combine!"

The Combine was the final threat in the battle against the fanatical terrorist group, Peace Corpse, and an enemy of the Avengers - it was a multi-entity dedicated to fulfilling the original aim of the Peace Corpse (which just happened to be a violent end of society via nuclear war, in order to create a better one in the aftermath).