Preheat the grill to medium-high heat (about 400°F/200°C).
Use kitchen shears to carefully cut the top shell of the lobster tails lengthwise down the center, exposing the meat but leaving the tail attached at the base.
Gently pry the shell apart and pull the meat upward, resting it on top of the shell.
In a bowl, mix together the melted butter, minced garlic, lemon juice, parsley, Old Bay seasoning (if using), and a pinch of salt and pepper.
Brush the lobster meat generously with the butter mixture. Reserve some for basting.
Place the lobster tails on the grill, meat side down, and grill for about 5 minutes.
Flip the lobster tails over and baste with the reserved butter mixture. Grill for an additional 3-5 minutes until the meat is opaque and cooked through, and slightly charred.
Remove the lobster tails from the grill and let them rest for a few minutes.
Serve the grilled lobster tails with lemon wedges and any extra butter sauce.