Souvlaki Hirino (Σουβλάκι Χοιρινό) is the pork version, and across Greece it is the common default: when someone orders souvlaki without specifying, this is what arrives. The reason is partly economic and partly that pork shoulder takes a marinade and a charcoal fire better than almost anything else on the grill counter. Cubed pork shoulder is marinated in olive oil, lemon, oregano, and garlic, then skewered and grilled. That marinade is the signature: the lemon brightens the fat, the oregano carries the herbal note that reads as Greek, and the garlic and oil tie it together without masking the meat.
Build it in order and the logic is clear. Shoulder is the right cut because its fat keeps the cubes moist over fierce heat where a leaner cut would seize. The marinade should coat the pork and rest long enough to penetrate, but not so long in the acid that the lemon starts to break the surface to mush. Cubes go onto the skewer evenly sized, then over charcoal hot enough to brown fast. Good execution gives you crusted, lightly charred edges over a juicy interior, the lemon and oregano present but in balance. Sloppy execution shows as pork left in acid until the texture turns chalky, a marinade so heavy on garlic it bites, or pieces cooked past doneness so the shoulder's fat renders out and leaves dry strings. The fat is the safety margin; cook it away and there is nothing holding the cube together.
This is the base from which most pork preparations branch. Left on the kalamaki it is eaten straight from the stick; the meat tipped into warm pita with tomato, onion, and tzatziki becomes the wrapped form; both of those build directly on this marinated, charcoal-grilled cube. The lamb version, Souvlaki Arni, is the older and costlier alternative and deserves its own article rather than being crowded in here. What defines hirino specifically is that olive-oil, lemon, oregano, and garlic marinade on shoulder: the rest of the dish is constant, and the pork and its cure are what carry it.