Common Blue (Polyommatus icarus) male.
I shot this little butterfly at Gious Kampos.
Yes, I know, I was there for the flowers, but a blue flutter-by is hard to ignore :-)
You can tell it's a male because the upperside of his wings are an iridescent blue-violet (barely visible in the photo), in females the upperwings are mostly brown with red-orange spots along the edges.
Best viewed Large, On Black.