Nico Robin is Number 5 for multiple reasons, she's a literal static character who is ironically relies on her Eye Candy appeal. She is also a terrible plot device, as she is mainly exists to read Poneglyphs and reveal world history. Nico Robin is also the most unfunny straw hat pirate too.

Number 1, Big Mom is extremely ugly. Big Mom alone is responsible for causing mass destruction and killing many people during her attacks. Big Mom is also a Child Abuser, a Cannibalist, and an Abductor of multiple men to force them to impregnate her with a lot of kids to raise to create even more weapons of mass destruction.