Paul Keres
Keres was always a man, and never missed the opportunity to say he was an Estonian, not a Russian. When he played at the annual Hastings tournament in 1954/55, a KGB man sat on a chair outside his room at night. He was there "to prevent the grandmaster being disturbed". Paul's demeanor at the board was always totally calm. From looking at him, you could not tell how much time he had left, or what kind of position he had. He had mastered the art of self-control, and his nickname amongst other players was 'Old Stoneface'.