Demons as a Species

Uh, like the title says, Demons as a Species. I was thinking about this, and it only made sense.
The demons of a particular species such as the Imps or the Caco, should all be different heights and weights. The Imp could anywhere from 5'9" tall to 6'8" tall. Not only this, but also, the Imps should all look basically the same, but have different looking bodies and such things. Example: the Imps in the old games looked all exactly the same. In Doom3, they should all look about the same, but have blood on their mouths from eating human flesh, or have spikes coming out at different parts of their bodies. Their eyes could glow a deeper or lighter shade of red.
For the Caco, they could be anywhere from 6'3" to 7' tall. The Caco could have colors ranging from ordinary red to to blood-red, to pinkish red.
For the Baron of Hell, he could be anywhere from 7' feet tall to a towering 8'6". His skin color could be anywhere the normal pink to a dark, garish, red. He could also have different facial features, like for anger, maybe, from ordinary "just angry" to "highly p*ssed off".
Sound OK?

http://www.doom2.net/single/monsters.html

Differing skins/models, ala the grunts in halflife?

Precisely.

thats cool...scientific names for the enemies of doom

That page is cool. It has loads of details and everything.