The main antagonist of JoJo no Kimyou na Bouken Part 4, Diamond wa Kudakenai.
A serial killer who uses his Stand, Killer Queen, to kill beautiful women for their hands, which he finds extremely attractive. He typically dresses in a suit with a distinctive skull-print necktie (example: post #404241).
After his identity is revealed to the main cast, he manages to switch all his identifying features with those of Kawajiri Kosaku and steals his identity.
He's the protagonist of the spinoff Dead Man's Questions.