Benjamin Jesty (1736 - April 16, 1816) was an English farmer notable for his early experiment in inducing immunity against smallpox using cowpox. The notion that those people infected with cowpox were subsequently protected against smallpox was not an uncommon observation with country folk in the late 18th century, but Jesty was one of the first to intentionally administer the less virulent virus. Jesty's experiment was met with hostility by his neighbors.