Here's a bunch of work on the main enemies from an as yet unpublished game! For much of early development these guys were called BaBs (Bread and Butters) or FULGs (Fucked Up Little Guys), as they were going to be the most basic and common enemy in the game.
My co-concept artist on some of these was Nikki Dawes. https://nikkidawes.com/ Some of these concepts are paintovers of 3D models by Nestor Villegas. https://www.artstation.com/3denvy My art director for these was Ben Zweifel. https://www.artstation.com/benzweifel