Petalioi (Greek: Πεταλιοί) is an island complex in south-east of Euboea, in the homonymous gulf.

The islands of the complex are: Megalonisos, Chersonisi, Avgo, Lamperousa, Louloudi, Makronisi, Pontikoniso, Praso, Tragos and Founti.

The name Petalioi derives from Petalios, the name of Megalonisos (the largest island) in antiquity.

In modern times, the islands were a property of the Greek royal family.

In 1915 or 1916, prince George II sold the islands to Greek shipowner Maris Empeirikos.