Alfred Langdon Elwyn (9 July 1804 – 15 March 1884) was an American physician, author and philanthropist. He was a pioneer in the education and care of people with mental and physical disabilities. He was one of the founding officers of the Pennsylvania Institution for the Instruction of the Blind in 1833 and founded the Pennsylvania Training School for Feeble-Minded Children in 1852. The community of Elwyn, Pennsylvania and the Elwyn Institute are named in his honor.