Mary Amelia Ingalls (January 10, 1865-October 20, 1928) was born near the town of Pepin, Wisconsin. She was the first child of Caroline and Charles Ingalls. She was the elder sister of famous author Laura Ingalls Wilder, who was best known for her Little House on the Prairie book series.

At the age of fourteen, Mary suffered an illness (variously described as scarlet fever, "a severe case of the measles", and as a stroke in her sister's unpublished memoir, Pioneer Girl) which resulted in lifelong blindness. Between 1881 and 1889, she attended the Iowa College for the Blind at Vinton, Iowa. There was one year in that interim where she did not attend the school, and the historical record is silent as to why, but she did finish the seven year course of study in 1889 and graduated. Then she returned home to De Smet, South Dakota and lived with her parents until their deaths. Later, she lived with her sister Grace and then Carrie. Contrary to the character on the "Little House" television series, she never married, nor did she become a teacher of the blind. She died on October 20, 1928 at the age of 63, as a result of pneumonia and complications from a stroke. She was buried at De Smet Cemetery.