The viral marketing campaign for The Dark Knight included: 1) Setting up fake websites like "I Believe in Harvey Dent" and "The Gotham Times" newspaper to build the film's story world. 2) Online scavenger hunts that revealed clues and new footage when solved. 3) Partnering with Burger King for a promotional meal and toys. 4) Releasing teasers and trailers online and with other films to generate buzz. 5) Leveraging Heath Ledger's death by focusing promotion on his iconic Joker role after he passed away.