One-Hit Wonder Actors You Didn't Know Passed Away

Poor Heather O'Rourke had her life and career cut terribly short. After starring as Carol Anne Freeling in the "Poltergeist" franchise, O'Rourke died from a "distinctly unusual" bowel defect, according to AP. She was just 12 years old. 

Defined by her oft-repeated "They're here" line, O'Rourke was described by her colleague Oliver Robins as a "precocious and a very intelligent girl for someone who was only five years old" (via Mama Mia). O'Rourke's manager Mike Meyer remembered how the young actress could memorize a 60-page script in an hour. Heather's special talents allowed her family to move from their trailer park to a house in leafy Big Bear, California.

O'Rourke's ill health began in 1987, which was attributed to the giardia parasite. Later, the actress was diagnosed with Crohn's disease, which was treated with cortisone, a steroid that's used to reduce inflammation, according to Everyday Health. However, what appeared to be Crohn's disease was actually a birth defect in her bowel. On February 1, 1988, O'Rourke's condition deteriorated rapidly, affecting her ability to swallow and breathe. As her digits turned blue from septic shock, O'Rourke entered cardiac arrest and suffered brain damage. That afternoon, young Heather was pronounced dead.

Born in Blackpool, England, John Mahoney had a lengthy career in film and television. However, he'll always be known for his character of Martin Crane in "Frasier," one of the 1990's biggest sitcoms. Martin is the blue-collar father of Frasier and Giles Crane, two endearingly pompous brothers who obsess over their various anxieties. 

Mahoney fell in love with the United States following a visit in 1951, which took him to Illinois, where his sister lived with her American husband. He returned to the country and state soon after, studying at the Western Illinois University, earning a master's degree in English. Years later, in 1979, Mahoney indulged his flair for acting and joined the Steppenwolf company, which was run by John Malkovich and Gary Sinise. Over the next decade or so, Mahoney appeared in films such as "Tin Men," "Say Anything," and "Barton Fink." 

After enjoying 11 seasons of "Frasier," Mahoney appeared in a handful of shows including "In Treatment" and "Hot in Cleveland." On February 8, 2018, The Guardian reported that Mahoney had died from throat cancer. Kelsey Grammer made an emotional comment on Mahoney's passing, "He was my father ... I loved him" (via People).

After a career in the military, R. Lee Ermey appeared in "Seven" and "Mississippi Burning." However, those were cameos compared to his performance as Gunnery Sergeant Hartman in "Full Metal Jacket." Louis Gossett Jr. won an Oscar for his turn as Sgt. Emil Foley, a fierce drill instructor with strong words and stronger fists. However, Ermey brought a whole new level of vicious intensity to his performance, which Empire magazine described as "staggering." 

Stationed at Parris Island, a U.S. Marine Corps training camp in South Carolina, Ermey's character taunts and berates his men without mercy, preying on weakness. He explains his methods to the men, "Because I am hard you will not like me, but the more you hate me the more you will learn, I am hard but I am fair." The grunt who endures the bulk of Hartman's cruelty is Private "Gomer Pyle" (Vincent D'Onofrio), whose mental health is reduced to tragic psychosis. When asked if his portrayal was realistic, Ermey said, "Yes it was, you have to kinda understand Val that we're sending these kids to Vietnam. I'm afraid that there was the occasional individual that would take it upon himself to use a little physical force that was not condoned by the United States Marine Corps."

After his roles in "Full Metal Jacket" and the aforementioned films, Ermey voiced Sarge in three "Toy Story" films and "Lock 'N Load," a documentary series about firearms. On April 15, 2018, Ermey died in Santa Monica. He was 74 (via New York Times). 

Ron Palillo is best known for his character Arnold Horshack in the sitcom "Welcome Back, Kotter," which ran for four seasons during 1975-1979 and launched the career of John Travolta.

Outside of his defining role, Palillo appeared in everything from "Ellen" to "Friday the 13th Part VI: Jason Lives." However, no turn matched his performance in "Welcome Back, Kotter," so much so that Palillo lamented the success of that character, "Everybody thought of me as Arnold Horshack. I resented Horshack for so many years" (via Big News Network). 

Later in life, Palillo moved to Palm Beach Gardens, Florida to be near his mother. Sadly, Ron Palillo died in that locale on August 14, 2012, aged 63 (via CNN). His agent Scott Stander described him as, "upbeat, fun, a great friend who loved theater, loved the fans and had a great sense of humor." Speaking with ABC News, former co-star John Travolta said, "Ron was a wonderful person and talent and helped catapult 'Welcome Back, Kotter' to great success. We will miss him."

Erin Moran is best known for her performance as Joanie Cunningham, Richie's plucky sister in "Happy Days," which ran for over 10 years from January 1974 to September 1984. After the short-lived spin-off show "Joanie Loves Chachi," Moran had sadly enjoyed the peak of her career (via Today). After three decades of small and irregular roles, Moran moved to a trailer park in 2010 with her second husband Steven Fleischmann. However, she would be ejected from the park because of drunken conduct, according to a Guardian obituary. Around this time, Moran was said to be working on a memoir called "Happy Days, Depressing Nights." A Page Six story found that several former child actors attempted to help Moran, but they were unsuccessful.

Moran died from cancer on April 24, 2017. She was just 56 years old. Her "Happy Days" co-star Ron Howard tweeted, "RIP Erin. I'll always choose to remember you on our show making scenes better, getting laughs and lighting up tv screens."

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Dominique Dunne's career was gaining big traction in 1982 because of her performance as Donna Freeling in "Poltergeist." Tragically, this would be her last big role, because her ex-boyfriend John Thomas Sweeney murdered her on November 4, 1982. Dunne was only 22 years old (via New York Times). 

Sweeney received a six-and-a-half-year prison sentence, but served just three years and seven months, according to Biography. Griffin Dunne, Dominique's brother and fellow actor, said, "This guy gets to be reinstated as the head chef in a restaurant as if nothing ever happened ... I don't want people to think, 'Hey, he killed someone but I'll have this steak anyway,'" (via Los Angeles Times).

This terrible turn of events is said to be part of the "Poltergeist" curse, which refers to the deaths of Dunne and fellow cast members Heather O'Rourke, Julian Beck, and Will Sampson.

If you or someone you know is dealing with domestic abuse, you can call the National Domestic Violence Hotline at 1−800−799−7233. You can also find more information, resources, and support at their website.

Andy Whitfield played the lead role in "Spartacus: Blood and Sand," which premiered in January 2010 and ran for three seasons, logging 33 episodes. However, the Welsh actor was diagnosed with cancer before the second season. After intense treatment and temporary remission, the cancer returned and proved to be terminal. Whitfield died in September 2011, aged just 39 (via Legacy). 

Whitfield suffered from non-Hodgkin lymphoma, which afflicted him for 18 months before the actor tragically succumbed. This struggle was documented in "Be Here Now," directed by Oscar-nominated filmmaker Lilibet Foster, who liaised with the Leukemia and Lymphoma Society, Stand Up To Cancer, and The Cancer Support Community (via ABC News).

Whitfield's death was announced by his wife Vashti, "On a beautiful sunny Sydney spring morning, surrounded by his family, in the arms of his loving wife, our beautiful young warrior Andy Whitfield lost his 18 month battle with lymphoma cancer."