When I first saw the link to the yahoo news article reporting his death. I was in disbelief, as I had to look at the article twice to just for by brain to register it. I expected to hear that Amy Winehouse, Britney Spears or Lindsay Lohan died before him. This is the guy who had a career that was really about to take off, we was already filming one movie and had another high profile film The Dark Knight in post production.
It just shows that some celebs have personal problems that do not get known to public. He kept his problems to himself and in many cases with addiction not getting his troubles known by friends or family is what does them in. While Amy and Britney we see their self destructive behavior constantly in the tabloids and blogs daily, not once did we hear that Heath Ledger was struggling with addictions or any health problems.