What do you get when you cross Lovecraft's Chthulu mythos and Heinlein's Puppet Masters and throw in a dash or two of Darker Than You Think? You get this nail-biting episode of The Outer Limits. As detailed by Bruce Rux, The Outer Limits was created by Leslie Stevens, whose father was a US Navy Admiral, so the denouement of this episode has added resonance.
After a billion, billion years, the strange forces of cosmic energy have put together nameless nuclei that met and fell to Earth where, although deformed by the fall, they plan to rule by infesting the bodies of powerful and influential humans. These 'alien things' can grow into the body of a man who is useful to them, but form ugly growths and make sickness of the men they cannot use in their attempt to take over.
Luis Spain is planted by the Government Intelligence Agency to get inside the clique of once respected men who are still in positions of power although converted by the invisibles they carry in their systems.
My apologies if this video isn't available for non-US readers, but I strongly recommend you track it down. Grant Morrison obviously did. Here's the link for the (Cht)Hulu page.