Joe Chill

Joseph Chillton (aka Joe Chill) was a small time crook who had the most servre affect on Batman, because he was the man responsible for killing Martha and Thomas Wayne (Batman's parents), however he regrets his decsion after he discovers he is the reason why the Dark Knight exists. Chill is provided a gun by Batman and proceeds to commit suicide (post-crisis). In the Pre-Crisis era, Chill dies before being able to annonuce Batman is Bruce Wayne. It is later revealed Chill was not just a mugger but a hitman under a order to kill the Waynes by Lew Moxon.