I'm probably going to get hate for this considering the character is...divisive, but Jason Todd, the Red Hood. I first got exposure to him from the animated film Under the Red Hood, I found him to be more realistic than Batman, and there is something incredibly sadistically satisfying about having a Gotham vigilante willing to put a rather permanent solution against an annoyingly common problem, I was smiling when he beat the shit out of the Joker with a crowbar. Just, the idea of this person, this masked man willing to go all out - to be Batman with guns, an antihero willing to put the villains through the same hell they constantly inflict on others.
A lot of comparisons were drawn between him and Deadpool for some reason, but Jason is a lot less silly (disregarding the New 52 and Grand Morrison versions of him). He's a deadpan, snarky, jerk with a hardened heart that ultimately means well and manages to tread the middle of morality. Sometimes he dips into a darker shade of gray, sometimes he's lighter, ultimately he's not so much a villain as simply an antagonist (sometimes even ending up a support character). It's not easy being an antihero in a setting that often has black and white morality, especially when a bunch of people killed you off through a vote, but if Jason hadn't died we wouldn't have the Red Hood I know and love.