Mary Temple Grandin (born August 29, 1947) is an American academic, inventor, and ethologist. She is a prominent proponent of the humane treatment of livestock for slaughter and the author of more than 60 scientific papers on animal behavior. Grandin is a consultant to the livestock industry, where she offers advice on animal behavior.

Grandin is one of the first autistic people to document the insights she gained from her personal experiences with autism. She is a faculty member with Animal Sciences in the College of Agricultural Sciences at Colorado State University.

In 2010, Time 100, an annual list of the 100 most influential people in the world, named her in the "Heroes" category. She was the subject of the Emmy- and Golden Globe-winning biographical film Temple Grandin.

Mary Temple Grandin was born in Boston, Massachusetts, into a wealthy family. One of the family's employees was also named Mary, so Grandin was referred to by her middle name, Temple, to avoid confusion. Temple's mother is Anna Eustacia Purves (later Cutler), an actress, singer, and granddaughter of John Coleman Purves (co-inventor of the aviation autopilot). She has a degree in English from Harvard University. Temple's father was Richard McCurdy Grandin, a real estate agent and heir to the largest corporate wheat farm business in the United States at the time, Grandin Farms. Grandin's parents divorced when she was 15, and her mother eventually went on to marry Ben Cutler, a New York saxophonist, in 1965, when Grandin was 18 years old.

Grandin has three younger siblings: two sisters and a brother. Grandin has described one of her sisters as being dyslexic. Her younger sister is an artist, her other sister is a sculptor, and her brother is a banker. John Livingston Grandin (Temple's paternal great-grandfather) and his brother William James Grandin were French Huguenots who drilled for oil. John Grandin intended to cut a deal with John D. Rockefeller in a meeting, but the latter kept him waiting so long that he walked out before Rockefeller arrived. The brothers then went into banking, and when Jay Cooke's firm collapsed, they received thousands of acres of undeveloped land in North Dakota as debt collateral. They set up wheat farming in the Red River Valley and housed the workers in dormitories. The town of Grandin, North Dakota, is named after John Livingston Grandin.

Although raised in the Episcopal Church, early on Grandin gave up on a belief in a personal deity or intention in favor of a more scientific perspective.

Grandin was not formally diagnosed with autism until her adulthood. When she was two, the only formal diagnosis given to her was "brain damage," a finding finally dismissed through cerebral imaging at the University of Utah by the time she turned 63 in 2010. While Grandin was still in her mid-teens, her mother chanced upon a diagnostic checklist for autism. After reviewing the checklist, Grandin's mother hypothesised that Grandin's symptoms were best explained by the disorder. Grandin was later determined to be an autistic savant.

When Grandin was a toddler, the medical advice at the time for a diagnosis like hers was to recommend institutionalization, a measure that caused a bitter rift of opinion between Grandin's parents. Her father was keen to follow this advice, while her mother was strongly opposed to the idea.