Chicken.
It's often really tasty in Greece, at least in rural areas, where the chickens have had normal outdoor chicken lives. It's usually simply prepared on the grill or rotisserie, in the classic lemon garlicky κοτόπουλο σκορδάτο (kotopoulo skordato), seasoned with plenty of oregano and baked with olive oil and potatoes. Also you may see κοτόπουλο αλά κρεμ (kotopoulo ala krem) with mushrooms, garlic, tarragon, brandy and cream, served over rice. Chicken gyros is common too, although most of that comes ready-to-cook from a factory.
Some useful chicken words:
στήθος κοτόπουλου (stithos kotopoulou) chicken breast
φιλέτο στήθους κοτόπουλου (fileto stithous kotopoulou) chicken breast filet
κοτόπιτα (kotopita) chicken pie
κοτόσουπα (kotosoupa) chicken broth
μπιφτέκι κοτόπουλο (bifteki kotopoulo) chicken burger
μπούτι κοτόπουλου (bouti kotopoulou) chicken thighs
συκώτι κοτόπουλου (sykoti kotopoulou) chicken livers
κοτομπουκιές (kotoboukies) chicken nuggets
φτερούγες κοτόπουλου (fterouges kotopoulou) chicken wings
κρέας από μπούτι (kreas apo bouti) dark meat
κοτόπουλο ελευθέρας βοσκής (kotopoula eleftheras voskis) free range chicken
κοτόπουλο τηγανητό (kotopoulo tiganto) fried chicken
ψητό κοτόπουλο (psito kotopoulo) roast chicken
άσπρο κρέας (aspro kreas) white meat
Image by foodswinesofspain