Arcadia or Arkadía (Greek Αρκαδία) is a region of Greece in the Peloponnesus. It takes its name from the mythological character Arcas.
Arcadia has its present-day capital at Tripoli. It forms the largest prefecture on the Peloponnesian peninsula. It currently covers about 18% of the entire peninsula, although it once extended to about 20 to 25% of the peninsula.