Thucydides’ continuing influence in contemporary political debates rests in large part on the perception that he offers a ‘realistic’ portrayal of human nature and of the impact of human nature on the behaviour of both individuals and states. This chapter analyses and contextualizes the two principal varieties of realism that have been attributed to Thucydides. First, the conventional realist reception, which reads Thucydides as a structural analyst of classic power politics. Second, a new political realism, which sees Thucydides as a witness to the complexity of politics and to the tragic consequences of that complexity. Finally, the chapter introduces a third possible mode of responding to the text, which brings back into the frame the question of what should be counted as ‘realistic’ in the first place and insists on ‘the usefulness of anachronism’ rather than the usefulness of lessons on reality.