With a distinctive high pitched voice, Ziffer has often voiced robots, aliens, squawking birds, cartoon characters, or other off-beat creatures. His mechanical resume began with V.I.N.C.E.N.T. in Disney's The Black Hole, followed by Johnny 5 in Short Circuit and its sequel. For the Star Wars prequels and tie-ins, he assumed the role of C-3PO from fellow voice actor Joachim Tennstedt (who returned to the part for The Force Awakens).