"The creatures of the Warp are just "aliens" too, but they are not life forms as we understand the term. They are not organic. They are extra-dimensional, and they influence our reality in ways that seem sorcerous to us. Supernatural, if you will. So let's use all those lost words for them... daemons, spirits, possessors, changelings. All we need to remember is that there are no gods out there, in the darkness, no great daemons and ministers of evil. There is no fundamental, immutable evil in the cosmos. It is too large and sterile for such melodrama. There are simply inhuman things that oppose us, things we were created to battle and destroy."

- Horus, WarHammer 40k


http://www.youtube.com/watch?v=-w4obDLTzWQ