He's a crew member that get infected, mutated.
You can see him jumping on the flamethrower dude with his suit on.
My take is that he's either one of the many f**ks up that the ampules/vials causes or tranforming himself into an Engineer.
and you are recognizing him on this tiny gif?
it could be fassbender, protecting a space jockey, or a specimen, don't know.
or maybe a guy in a jetpack. or the paper-boy delivering his newspaper in outer-space...
anyway, i can't see any deformation on this tiny pixel you call a person, nor a face, nor hair... nothing but jeopardy.