The Proto-Xenomorph made its first appearance in Prometheus, at the end when it burst out of the dying Engineer's chest. It was formed from an embryo the Trilobite
impregnated the Engineer with. Note how the birth of this Xenomorph is
different to a majority of other Xenomorph births, as it appears to be a
very basic yet humanoid form of the usual Xenomorph. The fact it spawns
almost fully developed makes it quite unique amongst other Xenomorphs
seen in the series; though the dog alienchestburster had arms and legs upon bursting. It still might be just a chestburster as it is small compared to its host but not to humans
which is why it looks like it is fully formed, however; it is possible
that this is still a small phase of growth, and it will grow to be
gigantic in size, much larger than the Trilobite and Engineer, as with
the standard Xemomorph's growth cycle proportions. Unlike normal
Xenomorph chestbursters, which "punch" their way out using the front or
top of their heads, this creature used the sharp back end of its head to
tear a way out. Also unlike normal Xenomorphs, it does not have an
inner jaw and instead has a human/Engineer tooth structure and gums. Its
"inner jaw" is merely an extra jaw that protrudes a short distance but
is much larger and more unwieldy than a Xenomorph's inner jaw. Whether
this "inner jaw" can be used as weapon is unknown. This version of the
Xenomorph will evolve over time into the regular version, which the
Engineers(Space Jockeys) use as a weapon of mass destruction.
The Goa'uld are parasites from the planet P3X-888, integrated within a host, most of the time a human.
The resulting creatures are a powerful race bent on galactic conquest
and domination, largely without pity, compassion or remorse.
The Reol are a race of humanoid aliens, supposedly from the Milky Way. They are a peaceful race who were almost wiped out by the Goa'uld. They were forced to abandon their home world because of the Goa'uld.
The Reol have a unique natural defense; one of their bodily secretions
is used to create false memories and illusions when it comes into
contact with a living creature.
The Electric Eel is a massive sea monster and the final villain in Journey 2: The Mysterious Island.
Living in the sea of the Mysterious Island. Most eels are small, but
because of the mystical powers of the island, large animals become small
and small animal become large. This means this Eel also becomes very
large. And hostile.