Carystus (//; Greek: Κάρυστος, near modern Karystos) was an ancient city-state on Euboea. In the Iliad it is controlled by the Abantes. The name also appears in the Linear B tablets as "ka-ru-to" (identified as Carystus). By the time of Thucydides it was inhabited by Dryopians.
Soon afterward Carystus refused to join the Delian League. The Athenians wanted Carystus to join the Delian League, but seeming as though it had been under Persian control, they refused. Athens would not accept a refusal, so they attacked and plundered Carystus. This forced Carystus to side with the Delian league. Athens employed this tactic frequently, as it was said to be better for the league. This way, a Greek city-state could not side with Persia and offer their city as a base, and also could not get the advantages of a Persian-free Greece without paying their share. The creation of the Delian league leads to the imperial nature of Athens that fueled the Peloponnesian War. Imperial nature tends to take on a modern association, however with the creation of the league essentially people of uneducated agricultural background were given the right to vote in the assembly. This version of Athenian democracy took on a role that allowed for a tyrannical nature of a seemingly egalitarian ideal. The league demanded submission to create a unified Greece, the only problem is that instead of creating a standing army or improved military strength to prevent further invasion, the Athenians under the direction of Pericles started the Periclean building projects that squandered funds and glorified Athens and Greece in their defeat of Persia. This misapplication of tribute from Attican city-states created the rejection of this idea by Sparta, and subsequently the Peloponnesian War, not securing Greece from an outside Persian attack, but opening it for an internal rejection of the league.
As an episcopal see, Carystus was initially a suffragan of Corinth, but in the 9th century it came to be associated with Athens and appears as such in the Notitia Episcopatuum composed under Byzantine Emperor Leo VI the Wise (886-912). A bishop of the see called Cyriacus was one of the signatories of the letter of the episcopate of the Corinthian province to Emperor Leo I the Thracian in 458.
- Antigonus (3rd century BC), writer
- Apollodorus (3rd century BC), comic playwright
- Diocles (4th century BC), physician
- Glaucus (6th century BC), boxer
- Homer. The Iliad, 2.539.
- Thucydides. History of the Peloponnesian War,7.57.
- Herodotus. Histories, 6.99.
- Herodotus. Histories, 8.112.
- Thucydides. History of the Peloponnesian War, 1.98.
- Michel Lequien, Oriens christianus in quatuor Patriarchatus digestus, Paris 1740, Vol. II, coll. 197-198
- Pius Bonifacius Gams, Series episcoporum Ecclesiae Catholicae, Leipzig 1931, p. 430
- Annuario Pontificio 2013 (Libreria Editrice Vaticana 2013 ISBN 978-88-209-9070-1), p. 859