Cheese in general. Some labels you may see include:
κατσικίσιο τυρί (katsikísio tyrí): goat cheese
μπλε τυρί (blu tyrí): blue cheese
παστεριωμένο (pasterioméno): pasturized
πρόβειο τυρί (próveio tyrí): sheep cheese
τριμμένο τυρί (trimméno tyrí): grated cheese
τυρί αγελαδινού γάλακτος (tryí ageladinoú gálaktos): cow's milk cheese
τυρί κρέμα (tyrí kréma): cream cheese
In the Odyssey, Polyphemus the Cyclops was actually a hard-working shepherd who made his cheese much the same way Greeks do today. As Odysseus describes, Polyphemus carefully divided his flocks of kids and sheep by age (which ensures a continuous supply of fresh milk). His dairy had shelves laden with cheese and bowls of whey. Odysseus and his men steal some, and against his men's sound advice, Odysseus decides to wait for the Cyclops to return home, curious to see what kind of being he was, and hoping to get a 'guest gift' according to the laws of hospitality.
Image by Zde