Hitman by Garth Ennis and John McCrea Omnibus #1

Plot

On the back streets of Gotham City, ex-military operative Tommy Monaghan has set himself up as a hired gun.

Surrounded by an odd assortment of friends and allies, the Hitman with a heart must deal with personal conflicts over honor and morals as he makes a living with a gun. But even with the telepathic ability to read his targets' minds, he still finds himself well over his head when he runs into some of Gotham's most notorious citizens such as the Demon, the Joker, and the Dark Knight himself, the Batman.

Plus, a vindictive mob boss from his past puts a contract out on Tommy. With his friends caught in the crossfire, he must find a way to take out the hired assassin and exact retribution against the mafia head. But even with his extrarodinary powers, the Hitman may find that a trained killer and a mob army is just too much for one man.