Dikastes (Greek: δικαστής, pl. δικασταί) was a legal office in ancient Greece that signified, in the broadest sense, a judge or juror, but more particularly denotes the Attic functionary of the democratic period, who, with his colleagues, was constitutionally empowered to try to pass judgment upon all causes and questions that the laws and customs of his country found to warrant judicial investigation.
In the circumstance of a plurality of persons being selected from the mass of private citizens, and associated temporarily as representatives of the whole body of the people, adjudicating between its individual members, and of such delegates swearing an oath that they would well and truly discharge the duties entrusted to them, there appears some resemblance between the constitution of the Attic dikasterion (court) and an English or American jury, but in nearly all other respects the differences between them are large. At Athens the conditions of his eligibility were, that the dikast should be a free citizen, in the enjoyment of his full franchise (ἐπιτιμία), and not less than thirty years of age, and of persons so qualified six thousand were selected by lot for the service of every year. Of the precise method of their appointment our information is somewhat obscure, but we may gather that selection took place every year under the conduct of the nine archons and their official scribe; that each of these ten archons drew by lot the names of six hundred persons of the tribe, or phyle, assigned to him; that the whole number so selected was again divided by lot into ten sections of 500 each, together with a one consisting of a thousand persons, from among whom the occasional deficiencies in the sections of 500 might be supplied.
To each of the ten sections one of the ten first letters of the alphabet was appropriated as a distinguishing mark, and a small tablet (πινάκιον), inscribed with the letter of the section and the name of the individual, was delivered as a certificate of his appointment to each dicast. Three bronze plates found in the Piraeus, and described by Edward Dodwell in his Travels, are supposed to have served this purpose. The inscriptions upon these plates consist of the following letters: Δ. ΔΙΟΔΩΡΟΣ ΦΡΕΑ, Ε. ΔΕΙΝΙΑΣ ΑΛΑΙΕΥΣ, and Β. ΑΝΤΙΧΑΡΜΟΣ ΛΑΜΠ, and also bear representations of owls and Gorgon heads, and other devices symbolic of the Attic people. The thousand supernumeraries had in all probability some different token, but of this we have no certain knowledge.