Mix mashed potatoes, stuffing, eggs, Parmesan cheese, poultry seasoning, 1 teaspoon salt, and pepper together in a large bowl until well combined.
Pour panko bread crumbs into a wide shallow bowl. Form 2 tablespoonfuls of stuffing mixture into a ball. Roll in bread crumbs until well coated. Repeat with remaining stuffing mixture.
Heat oil in a deep-fryer or large saucepan to 350 degrees F (175 degrees C). Fry stuffing balls, 4 at a time, until golden brown, 6 to 8 minutes. Transfer to a cooling rack; sprinkle with sea salt.
