It's a little known fact that the first Die Hard film, in all it's eternal glory, was actually based upon a novel from 1979 entitled Nothing Lasts Forever, written by Roderick Thorp. Despite the Bond-esque title, the book actually focused on Detective Joe Leland, whom eventually made his way to the big screen as (you guessed it) Police Officer John McClane.
John McClane has developed over the four Die Hard films and numerous games from "Wrong Guy, Wrong Place, Wrong Time." to Big Damn Hero. The trailer for Die Hard stated that:
The last thing McClane wants is to be a hero, but he doesn't have a choice.
In Live Free or Die Hard (Die Hard 4.0 outside of the US), however, McClane himself states he shows up, kills the bad guys and saves the day because:
"There is nobody else to do it."
This considered, McClane still has a number of problems: From day one he and his wife, Holly Genaro, have been riding through a turbulent marriage that has seen at least one seperation and a divorce. In Die Hard with a Vengeance, McClane was described by his CO as being: "two steps away from a full blown alcoholic" to which a hungover McClane jokingly mimes "one step."
Live Free or Die Hard saw McClane struggling with an abrasive relationship with his grown daughter Lucy Gennaro-McClane, up until the point where she is kidnapped, and John busts in and saves her. She's understandably somewhat forgiving of his faults by this point.
John McClane is one of cinemas most beloved cops, and his gritty, realistic attitude and outlook have captured the hearts of millions. Styled as a regular cop who is frequently caught up in the worst situations by chance, McClane lives in the 'now' of these situations with no time to prepare with suave tux's and cheesy one liners, resulting in a hero that Entertainment Weekly refers to as the "anti-Bond", essentially a hero that any of us could be as opposed to the perfect chiseled super spy.