Rinse the parsley, pat dry, and finely chop. Finely chop the shrimp. Mix the parsley and the shrimp with the softened butter until thoroughly combined.
Rinse the lemon under hot water. Finely grate the zest and squeeze the juice from the lemon. Season the butter with the lemon zest, lemon juice, salt, and pepper. Chill the butter in the refrigerator until ready to use.