We left our US to European electric adapter behind at a hotel in Heraklion. This didn't effect our laptop or iPad, which had their own adapters. But our iPhone and camera rechargers were US only plugs. Found a shop in Naxos Town, with lots of small appliances - including US/UK to European adapters. Cost was 5 euros apiece, so we bought two.
The shop is easy to find in Naxos Town, even though all the signs are in Greek. It's toward the bottom of the seafront area (away from the ferry port), and then a couple blocks in on Sokratous Papavasiliou street. If you have internet access, get Google map directions to the "Coffee Island" shop (there's only one), and the electric shop is right across the street. If you can sound out Greek characters, the shop is called Electrika Sergis. Looks like HAEKTPIKA SEPTHS (with my apologies the people of Greece!)
Note 1: Sometimes a larger hotel than ours might loan you one.
Note 2: All our appliances accept 220volts or 110volts, The adapter won't change 220 into 110. Check the label on your gadget or appliance to be sure it can accept 220V before plugging it in, to avoid damaging your appliance. But you probably already knew that!