My story is set on a planet which has been taken over by Aliens, the only problem is, I don't know what they look like! I know all their abilities and plans but not their appearence. I want to avoid the typical 'Greys' as Aliens very similar to them appeared in Doctor Who recently and this story already has some similarities to that episode. Also due to me being a big fan of Doctor Who, my friends who read it will make the connection almost instantly. These Aliens need to have an imposing look and be reconsiable from a distance, so say we see an army of them marching across the Dessert, miles away, my characters will need to see them and instantly reconise them. A humanoid shape will be good. This is a big problem for me as I need these Creatures to begin my story. Any ideas for appearence/names?