Hi! There are 4 pirate bosses.
1. Ron the Ripper and it drops Ron the Ripper's Sabre
2. Deadeye Devious and it drops Deadeye Devious' Eye Patch
3. Lethal Lissy and it drops Lethal Lissy's Shirt
4. Brutus Bloodbeard and it drops Brutus Blodbeard's Hat
With the 4 itens you can obtain the addon 2 of Pirate outfits: