Daemonites

The Daemonites are an alien race that have been trying to take over the Milky Way for countless ages. This is what led to the Kherubim/Daemonite War, a conflict in which an alien race called the Kherubim tried to stop the Daemonites from conquering the galaxy. The conflict eventually made its' way too earth. Daemonites cannot survive long in earth's atmosphere, the only way they can live on earth is to use a human host in which they "possess."

Homeworld
The Daemonite home world is called Daemon, a world with a toxic atmosphere. Although to them it apparently is not toxic, but an earth-like atmosphere is toxic to them.

Physical appearance
Daemonites resemble green lizard-like creatures with bug-like faces. In fact, one of the common insulting racial slurs that the Wildcats refer to them as is the "Bug-faces."