She died of lung cancer Wednesday morning at her Fort Bragg home on California's north coast, said friend Bruce Lewis. Her son, Matthew Ned Conlon, was by her side.
Conlon was picked to play the small, but pivotal role of Bonnie Blue Butler in the 1939 Civil War epic at age 4. Her character's death in a fall from a pony irrevocably damages Rhett and Scarlett's tumultuous marriage.
Conlon also voiced the young doe Faline in Walt Disney's "Bambi" three years later. It would be her final film role.
"My mother decided she wanted me to have a normal childhood," she wrote on her blog, which talked about her brief career and a memoir she published last year on her "Gone With the Wind" experience. She often joked with interviewers that she had "peaked at 5."
The Los Angeles native graduated from the University of Southern California with a degree in communications and spent two years editing California Pictorial magazine. She moved to Mendocino County 30 years ago, working as director of the Kelly House museum and as a publicist for the Mendocino Coast Chamber of Commerce and the Little River Inn.
Conlon stayed in touch with her "Gone With the Wind" family. On Sunday night, she took a call from Olivia de Havilland, who played Scarlett's sweet-hearted nemesis Melanie in the film, her son said.
"It's amazing because she is so much more than Bonnie Blue Butler, but ... that is what she is remembered for, and it's a pretty great thing to be remembered for," Matthew Conlon said. "Nobody told it better than Mom - when you debut in 'Gone with the Wind,' it's downhill."
She told the Santa Rosa Press Democrat last year that she had few clear memories of her time on the studio lot that served as the set for the fictional plantation Tara.
One was watching her stunt double for the pony scene, a male dwarf, smoking a cigarette while dressed in a reproduction of her riding habit costume. Another was being scratched by Clark Gable's mustache in the scene where Rhett Butler hugs and kisses his cherished daughter.
"As the years have gone by, I realize it's an honor, and it's so humbling," she had said. "I had nothing to do with it. I was 5. They said 'Stand here. Do this.' And yet it's resulted in this incredible experience."
Conlon spent much her adult life gamely reprising her Bonnie Blue days for "Gone With the Wind" enthusiasts. She appeared at parades, retrospectives, museum exhibits and anniversary celebrations for the film in both Georgia, where the movie was set, and in California.
Just last year, she donned her hoop skirt and petticoat again to visit a middle school that was studying the Civil War. "It wasn't her whole life, but she had a lot of fun with it," Lewis said.
Conlon is survived by her son and a daughter, Katie Conlon Byrne. A memorial service is planned for next week in Fort Bragg. Another will be held in Los Angeles on Sept. 22 and a third at a later date in Marietta, Ga., home of the Gone With the Wind Museum.