Pre-heat grill, over high heat, or preheat oven to 425°F.
Cut 4 sheets of foil about 12-inches long.
Divide shrimp, garlic, sausage, corn and potatoes evenly over the foil sheets.
Drizzle with oil; add Old Bay seasoning and season, to taste, with salt and pepper; toss gently to combine.
Top each mixture with parsley, lemon and a tablespoon of butter.
Fold foil packets crosswise over the shrimp boil mixture to completely cover the food.
Roll top and bottom edges to seal them closed.
Place foil packets on grill and cook until just cooked through; about 15 to 20 minutes or place in pre-heated oven and bake for 30 minutes.