I can remember having read a sci fi comic story that seems to fit in perfectly with the plot of the original "Night of the Living Dead".
The story starts with a space vessel traveling to venus to search for a missing survey vessel.
They find the missing ship in orbit, no one aboard and all organic materials have disappeared.
They find that a sort of vapor like cloud that moves under its own control is ingulfing their vessel.
During their escape they skim low over the surface of venus and the surface is covered with layers of humanoid bodies descicated and apparently having starved to death.
The answer to the mystery is that the Venusians had discovered imortality, but having no way of controling procreation the planet's resources could not support its ever growing population.
Finally the population was left a mass of starving undead corpses the withered arms reaching upwards.
The combined remnant of their great mental powers had formed the etcoplasm like mist that was driven by pure animal hunger. It eats everything organic that it contacts, and if it takes over a living being he becomes a voracious cannibal, finally eating his own flesh.
This fits with the TV news report in "Night of the Living Dead" of a strange radiation following a venus probe back to Earth.
I've often wondered if there was a connection, perhaps the writer of NOTLD had read that story many years earlier and it was at the back of his mind.