His numerous feature film credits include Mad City starring opposite Dustin Hoffman and John Travolta, Dead Man Walking with Susan Sarandon, The Scarlet Letter starring Demi Moore and Far and Away with Tom Cruise and Nicole Kidman. Other film credits include Miracle on 34th Street, Last Action Hero, Hoffa and The Natural with Robert Redford, among others.
For television, Prosky's credits include The Murder of Mary Phagan, a mini-series with Jack Lemon as well as many guest appearances on shows such as Frasier and The Practice.
Born in Philadelphia, Prosky studied economics at Temple University, joining the Air Force when the Korean War began. After a family tragedy earned him an early discharge, he returned home to run the family grocery store. In his spare time, he toyed with theater, a hobby which soon blossomed and earned him a scholarship to the American Theater Wing in New York. His stage career has taken him on tour as part of the first American acting company to perform in the Soviet Union, and he has received several Tony nominations in addition to a New York Outer Critics Award.