To me, "evil" character isn't character who murders everything cute and nice, and definitely not a murder-hobo, but as was said above, an egotist. Egotist who is cynical, and hopefully intelligent, someone who manipulates, twists and corrupts.
100 % agree. For me an "evil" character also in an RPG has Dark Triad Personality Traits, which doesn't mean that person have to be a slaughterer, but e.g. shows a strategic focus on self-interest, lack of empathy for others, indifference to morality, tendencies to manipulate, et cetera pp
And not necessarily all of these character traits together, one more, one less. It depends, on "how" evil a character should be.
I am not going to play an evil run, but I fully support people, who wish to, to get more content for the evil path.