Gian Maria Volonté and Riccardo Cucciolla
These two actors delivered excellent performances. I watched this movie because of Volonté, because I'm a huge fan of his screen presence and acting style, but Cucciolla's subdued, less histrionic performance was an excellent counterpoint to Volonté's more showy work. They complemented each other very well on the screen; Cucciolla was especially poignant in the last third of the movie, when they're sentenced to death. You can see all hope and strength to live slowly abandon him as the story progresses. I think he had fewer lines than Volonté, but he expressed so much with just his eyes.
This is an excellent movie, there are many reasons to watch it, but above all because of the fine acting.
This world is a comedy to those that think, a tragedy to those that feel.