Set oven to 400°F (205°C). Use foil to line a shallow, rimmed sheet pan.
Arrange thawed crab legs in an even layer on the baking sheet. Evenly distribute the juice of 1 lemon and the minced garlic over them. Slice 1/4 cup (4 Tbsp) of butter into small pieces and scatter them evenly atop the crab legs. Finally, evenly dust the crab legs with the lemon pepper.
If using pre-cooked crab legs (as indicated on packaging): Bake, uncovered, at 400°F (205°C) for 5-7 minutes.
If using raw, uncooked crab legs: Bake at 400°F (205°C) for 10-15 minutes.
Serve immediately while hot, accompanied by extra lemon wedges and melted butter for dipping.