Eucleides

Eucleides () was eponymous archon of Athens for the year running from July/August 403 BC until June/July 402 BC. His year in office was marked by Athens's official adoption of the Ionic alphabet. There is some evidence that he may have been personally involved in this decision.

== Archonship== During his archonship Athens abandoned the Attic alphabet in favour of the Ionic alphabet, which included the letters eta, phi, psi, and omega, but lacked heta. This alphabet had already been employed unofficially in inscriptions and other texts for some years, but was now adopted for official Athenian inscriptions. Although some Athenian inscriptions from before Eucleides's archonship already used the Ionian alphabet and others use the old Attic alphabet after it, the majority reflect the switch and Eucleides's archonship is thus an important milestone for dating Athenian inscriptions.