Beings of Extra Terrestrial origin Adversary to human race. Official name for the grotesque alien creatures of the Muv Luv visual novel/anime franchise. Identification tips of most BETA types: multiple limbs on lower body, phallic head, giant mouth with only molars. All other alien organisms associated with identified BETAs are their more dangerous cousins.
They can and will consume everything in their path if not stopped by 36MM chaingun fire. Don't panic if you think this description fits some humans you know.
A: You're such a dickhead for helping yourself to my fridge.
B: I'm practicing my BETA imitation routine! (bites A)