Peel and de-vein your raw shrimp if they aren’t already. Place the shrimp in the center of a long sheet of foil. Add the butter, garlic, lemon juice, sea salt, dried parsley, and red pepper flakes (if you’re okay with some heat).
Fold the foil into a packet and place on the preheated grill. Replace the cover and grill 8 to 10 minutes. Flip the foil packet and continue grilling until shrimp are pink and cooked through, about 3 to 5 minutes.
Remove from heat and place on a baking sheet or cutting board. When cool enough to handle, open the foil packet and give everything a big stir. Serve shrimp with choice of side dishes or cocktail sauce.