Periander consults his dead wife at the Acheron
Herodotus (5.92) says the tyrant Periander of Corinth sent to the oracle of the dead on the river Acheron to ask his dead wife Melissa where a guest's deposit was hidden.
600 BCE · 39.24, 20.48 · status: legend
The account
Melissa's ghost refused to answer, saying she was cold and naked because the clothes buried with her had not been burned. As proof she gave a detail only Periander could know. He then had the women of Corinth stripped of their finest clothes and burned them for her, and on a second consultation she told him where the money was. The story is the oldest literary account of a consultation at a Greek necromanteion.
The sceptical view
Herodotus tells it at second hand, as part of a speech meant to show the cruelty of tyrants, more than a century after the events.