Boo Radley — To Kill a Mockingbird (1962)

In his film debut, Duvall played the reclusive, misunderstood Boo Radley with no dialogue and only a few brief scenes — yet the performance is unforgettable. The moment he appears in Scout's room to smile at the unconscious Jem is one of cinema's most tender images. It was an audacious choice for a screen debut: to anchor a pivotal dramatic moment through pure physical presence. The performance announced a major talent.