11. Heather O’ Rourke
The Poltergeist star passed away when she was just 12 years old. O’Rourke originally became ill early in 1987. Unfortunately, the actress was misdiagnosed by doctors that believed her to have Chrome’s disease. Less than a year later, O’Rourke once again became sick. While getting ready to leave for the hospital the following morning, the young star collapsed and suffered a cardiac arrest while being transported to the hospital. The star died the following day from a second cardiac arrest during surgery to remove an acute bowel obstruction.