This paper aims to frame the figure of the judge in the context of the history of trials in ancient Greece by examining two lines of research. The first detects the gradual transfer of the judicial function from the holders of political power to specific figures of judges. The second highlights the change from a mode of judgment based on binding evidence to a judicial decision based on the free conviction of the judge. These conceptions are then summarily illustrated in the characteristics of the judicial function in the three better known cities, namely the Cretan Gortina, Sparta and Athens. The paper moves on to an examination of the opinion of some leading philosophers who have dealt with this theme: Hippodamus, Plato, Aristotle. Finally, a reference to a typical figure of the Hellenistic world is considered: the foreign judges.