Basically, what word might be a reflection of the word used to describe the energy sapping parasites from the awesome Metroid series (minus Other M)?

Just a random curiosity.

Energy Vampire
Lifeforce Leech
Parasitic Jellyfish

Children.

Proles, plebs.

I second that, that and adults that act like children.

Not sure what you guys are on about. Well, I was thinking of a less common single word, like how scientists often use foreign pieces of words and according to their correspondence to the labeled in question fit those words together to get a single word.

A google search turned up that Metroid means "Ultimate Warrior", but in Chozo language. A bit disappointing, as I wanted to know what inspired the name itself, not what the name is virtually inspired by.

Strigiscombibonavitus

strigis - Latin for vampire
combibo - Latin for suck
navitus - Latin for energy

Animatransvoroectoparasite

anima - Latin for lifeforce
transvoro - Latin for absorb/devour
ectoparasite - an external parasite

From Wikipedia:

"The name of the game is a portmanteau of the words "metro" (as in rapid transit) and android, and was meant to allude to the mainly underground setting of the first game as well as its robot-like protagonist."

[metr-] - Greek for womb/uterus
[-oid] - a suffix meaning resembling/like

or:

metro - a tunnel or underground passageway
id - the part of the psyche, residing in the unconscious, that is the source of instinctive impulses that seek satisfaction in accordance with the pleasure principle