My definitions come from dealing with and healing from narcissists.
And, unfortunately, the media has done its best to change the definition of psychopath to Norman Bates and silence of the lambs. I would not call these people narcissists / psychopaths.
The defining characteristic is a lack of warm empathy.
So, they are not "dead" inside. They have feelings, for themselves. Other people, they have as much feeling for as one would their computer.