With all that said, bat tattoos are symbolic of a fairly wide range of ideals: death, evil, rebirth, and prosperity, to name but a few.
If you are inclined towards the “creepy” side of things, a full-on realistic “3D” tattoo of a bat hanging upside down with its eyes glowing in the dark would make for an appropriately scary and wince-inducing image.
Lots of heavy black in the background would help to convey their typical dwelling, not to mention provide a nice contrast to help their eyes “pop”. To further emphasize their inherently menacing qualities, their teeth, impossibly sharp and perhaps covered in blood, could be exposed via a devilish sneer.
Large ears, a snubbed nose, and thin-fleshed wings draped over their bodies are also features that can help to accentuate the sense of foreboding and dread.
Anthropomorphism seems an insult to most animals as they really do not need to be “humanized” in order to be appreciated or relatable, however, such an approach could apply to your bat tattoo.
It would be a good way to “take the edge off” their fearsome image if, for example, you had a cartoon style bat smiling brightly while standing upright and guzzling a frothy-topped beer.
Similarly, Sesame Street’s “The Count”, with his high-collared coat and exposed (yet ridiculously cute) fangs, makes for a marvelously charming tattoo design idea. (Vampires are, after all, inherently charming.)
Instead of inspiring fear, this adorable numbers-loving “bat-in-human-form” is redolent of childhood and virtually guaranteed to induce smiles and pangs of unbridled nostalgia.