Once you’ve made the choice to get an evil tattoo meaningful to you, you can start the exciting process of finding a design or symbol.
There is a trend to do large portraits dedicated to the dark forces that play a role in fantasy literature and movies. The all-seeing eye of Sauron or evil dragons can be striking in their artwork and meaning.
Evil sprites, elves, and imps are a great choice if you want to depict an inner mischief without committing to an evil choice.
There are certain animals that are also associated with evil that you could consider. Wolves, werewolves, vampires, bats, and snakes all suggest evil, and because you are exploring the fantasy space, you can make them as grotesque or unusual as you want.
Check out fantasy films or novels for more ideas — there are often evil characters or beings that could spark a great tattoo idea.