Heather Michele O'Rourke was born on December 27, 1975 in Santee, San Diego, California, to Kathleen, a seamstress, and Michael O'Rourke, a construction worker. She had German, Danish, English, and Irish ancestry.

Heather entered American cinematic pop-culture before first grade. She was sitting alone in the MGM Commissary waiting for her mother when a stranger approached her asking her name. "My name is Heather O'Rourke," she said. "But you're a stranger, and I can't talk to you". When her mother returned, the stranger introduced himself as Steven Spielberg. She failed her first audition when she laughed at a stuffed animal Spielberg presented her with. He thought she was just too young (she had just turned five), and he was actually looking for a girl at least 6 years old, but he saw something in her and asked her to come in a second time with a scary story book. He asked her to scream a lot. She screamed until she broke down in tears. The next day at the commissary, Spielberg told her and her family, "I don't know what it is about her, but she's got the job." She instantly became a star overnight and was easily recognized at her favorite theme park, Disneyland, and everywhere in California. In the years that followed, Heather was a familiar face on TV in Happy Days (1974) (1982-1983), Webster (1983) (1983-1984), and The New Leave It to Beaver (1983) (1986-1987), three shows in which she had recurring roles. In 1986, the highly anticipated sequel to her first movie, Poltergeist (1982), Poltergeist II: The Other Side (1986) debuted in theaters; it was her riveting performance in this film that cemented her a place in Hollywood history. In January 1987, Heather began to have flu-like symptoms and her legs and feet swelled. She was taken to Kaiser Hospital, and they confirmed it was only the flu, but when symptoms continued, they diagnosed her as having Crohn's Disease, a chronic inflammation of the intestine. She was on medication throughout the filming of her next project, Poltergeist III (1988), and her cheeks were puffy in some scenes. She never complained during filming and did not appear sick to fellow cast members.

When filming was completed in June, Heather and her family went on a road trip from Chicago, to New Orleans, to Orlando and all the way back to Lakeside where they lived at the time. Heather was well until January 31, 1988, Super Bowl Sunday. She was unable to keep anything in her stomach and crawled into bed with her parents that night, saying that she didn't feel well. The next morning, February 1, sitting at the breakfast table, she couldn't swallow her toast or Gatorade. Her mother noticed her fingers were blue and her hands were cold. Kathleen called the doctor's and was getting ready to put her clothes on when Heather fainted on the kitchen floor. When the paramedics came in, Heather insisted that she was "really okay" and was worried about missing school that day. In the ambulance, Heather suffered cardiac arrest and died on the operating table at 2:43 p.m. at the tender age of 12. Of all her achievements, Heather was proudest of being elected student body president of her 5th grade class in 1985.