First published back in 1987, this was probably [along with Watchmen and The Dark Knight Returns] the formative comic book of my burgeoning adolescence. In the very first issue, the hero The Question/Vic Sage [portrayed as kind of an S.O.B.] is beaten half to death by the martial arts mercenary, Lady Shiva, and some thugs, shot in the head with a pellet gun, and thrown into the river to drown. Then he dies. That's the end of issue #1.
Hooked, I was. Sold, all the way.
Of course, he lived. And then the series got really good. Deeply infused with eastern [mostly Zen] and western philosophy, it started me down a path I remain, for good or ill, to this day. The monthly recommended reading list in the letters column lead me to Zen and the Art of Motorcycle Maintenance, Way of the Peaceful Warrior, The Tao of Physics, A Scanner Darkly, Invisible Man, The Art of War, and Shambala... my mind was warped appropriately, and the rest is [my] history.
And plus, there was lots of martial arts and kicking people in the face.
The Question, Vol. 1: Zen and Violence: Dennis O'Neil,Denys Cowan,Rick Magyar