Silene sartorii
This plant immediately reminded me of Silene conica and that wasn't fra out because according to World Plants online Silene conica ssp sartorii is the accepted name. But Kew says that Silene sartorii is the accepted name and Silene conica ssp sartorii is a synonym. I wish taxonomists would speak to each other and agree a bit more.
Silene sartorii is found in a few places on the Greek mainland but by far the majority of sites are on many of the islands in the Aegean sea.