According to BBC News, Conlon passed away from lung cancer on Wednesday.
She started her film career at the age of 5 with the role of Bonnie Blue Butler in the classic 1939 movie starring Vivien Leigh and Clark Gable.
Conlon also voiced the character Famine in Disney's Bambi.
As an adult, she worked as a publicist for a chamber of commerce and as a director of a museum.
Speaking to the Santa Rosa Press Democrat in 2009 about her role in Gone With The Wind, she said: "As the years have gone by, I realise it's an honour and it's so humbling."
