Heath Ledger died due to accidental drug overdose. Reports even suggested that the actor was depressed after playing Joker in The Dark Knight. The character took a toll on his mentally and physically, so much so, that he suffered from insomnia. However, this rumour was dispelled in a documentary about the actor.source https://www.indiatvnews.com/entertainment/hollywood/heath-ledger-death-depression-symptoms-joker-in-the-dark-knight-626306
