Here is a look at the pro-packaging for NECA's upcoming "Deacon" figure from Prometheus. Aside from the figure itself, it also includes the severed "Engineer" head seen in the film.
I know that the arrival of "the Deacon" (don't know why he's called that, but okay...) in the film was a nice little "easter egg" and his full explanation wasn't spoon fed to the audience (which is why I liked the film and so many other people hated it), but in my mind, this is the first "alien".
If this is the first time the "vials of mass destruction" are found, then I assume that all the different events and alien manifestations that lead up to the birth of Deacon are the events that lead to what we now know as the aliens from the films. Maybe that's debatable, but that was my personal interpretation.
But, I digress... This is an action figure blog, so let's see the figure! (Or, prototype figure, in this case...)