If you're a supervillain, and male, you're probably not going to be one of the "beautiful people." Odds are, your mug is going to fall into one of two categories:
1. Long and narrow, with a knobby, pronounced chin, a high forehad, eyes that are way too close together, arched, pointy eyebrows, and possibly some sort of ill-advised facial hair, like a pencil-line moustache. Sinestro, Felix Faust, Loki, the unrejuvenated Vulture and the pre-Robinson Shade all fall into this category. (Although Loki was quite the looker in his very first appearance; remind me to post about that some time!)
2. Broad, fleshy, and brutish, with a squashed-in, bulbous nose (optionally broken), a full square acre of space between the nose and the upper lip, and either no eyebrows at all or comically bushy ones that meet over the bridge of the nose. That'd be your Kingpin, Sandman, Hydro Man, Blockbuster, Hammerhead, Attuma, Blastarr type of face.
Ironically, a lot of these villains would look infinitely more intimidating if we couldn't see their faces. Facelessness, be it complete or partial, lends an air of mystery to a villain -- and more importantly, it makes them seem less identifiably human. That taps into mankind's primal fear of "the other" and ratchets up the intensity of their threat in our minds.
Case in point: old Aquaman villain, the Scavenger (seen here in "Who's Who" #20, October 1986).
Scavenger's costume was no great shakes to begin with. Pretty blah. Although I like the belt... I could match that thing up with some leather pants and a pirate shirt and have a mind-blowing night out on the town. But the rest of Scavenger's outfit basically sucks. It's a leech costume.* Leeches aren't scary. A little gross, maybe, but not frightening. He may as well be dressed as a tapeworm. But the worst part is the goofy helmet. Because it's a diving helmet, with the window part all dolled up to look like a leech's mouth. With Scavenger's big, ugly mug peering out of it.
It doesn't make him look like a leech. It makes him look like he's being devoured by a leech. His battle cry should be "This thing is eating me alive oh dear God why won't anybody help me!"
Another good example of this phenomenon is Firefall, from "Rom" #4 (March, 1980). The Firefall armor used to belong to Rom's "special friend" Karas. (Greek, huh? Sexy!)
Note how the only indication of facial features on Firefall's noggin is the two flashing lights for his "eyes." Not a bad piece of alien cyborgery, huh? But then Karas dies, and the evil Dire Wraiths get ahold of his cyborg body. The Wraiths somehow excise all of Karas' fleshy bits out of the armor, probably using those big metal cracker deals they give you at lobster restaurants, and then they stick it on a criminal named Archie Stryker. Archie has one of the worst cases of Sal Buscema Face I have ever encountered. Sal gave him the Deluxe Package: pug nose, beetling forehead, teensy-weensy eyeballs, a mouth like a rockfish, and as a bonus, an intricate web of stringy drool is visible whenever he screams at somebody. Which is often. And this bleary, sweaty, "angry drunk" face is fully visible through the Firefall armor's visor.
It doesn't convey "evil" so much as "seriously pissed because the bartender cut me off plus that bitch in the corner booth won't give me her phone number, aw she's prob'ly a lesbo anyhow C'MON BUDDY JUST ONE MORE SCOTCH ROCKS I SWEAR I'M GOOD FOR IT." After his battle with Rom, he's probably going to make some harrassing calls to his ex-wife, punch another hole in the wall of his crappy hotel room, pass out drunk on the floor and wake up the following afternoon soaked in urine.
Call me old-fashioned, but I think Firefall looked better with just the two little blobs of light.
*I have since been informed that the Scavenger is meant to look like a lamprey. I think my point remains valid.