Kali is a Hindu goddess often misconstrued as a goddess of death. While she does bring about the death of the ego and demons, she does not kill humans. She is the counterpart of the more violent deity Shiva the destroyer, both of whom are the destroyers of unreality. Kali is depicted as a woman with a garland of skulls or heads, and dismembered arms, because the ego arises out of identification with the body. She also is usually seen with black or dark blue skin, which symbolizes the womb of which all creation arises and into which all creation will eventually dissolve into. So she is often mistaken as a fearsome deity, she is actually a motherly figure.
As a tattoo Kali is often done in American traditional style, neo-traditional, black and grey, or realism.