Joan Olive Robinson Hill (February 6, 1931 – March 19, 1969) was a socialite and equestrian from Houston, Texas. Her unexplained death at age 38 led to her husband, John Hill, becoming the first person to be indicted by the state of Texas on the charge of murder by omission. The case precipitated a series of events that included the 1972 murder of John Hill and, two years later, the fatal police shooting of the man accused of that murder. Adopted as an infant by wealthy oil tycoon Davis "Ash" Robinson and his wife, Rhea, Joan became an equestrian at a young age. She excelled and continued the sport into adulthood, ultimately winning several national titles.