Can't remember the species name, but the tip of their nose is physically connected to their chin.
How were they supposed to eat?
You mean this fool?
The Tak Tak, from VOY's "Macrocosm". Frankly, there wasn't anything about them that wasn't
Also, I just have to mention Armus, from TNG's "Skin of Evil". His personality was certainly menacing, but honestly? He just looked like an oily trash bag. Picard's face pretty much sums it up:
"What the hell is this?"