Jack the Ripper

Jack the Ripper is an antagonist featured in Part I: Phantom Blood. He was inspired by the historical character who still remains a mystery today.

Personality
Jack the Ripper is shown to have a gentlemanly facade, able to convince a woman to walk with him on a dark night. When he reveals his true colors, he does not hesitate to stab the unarmed woman to death. As a vampire, this trait becomes even worse, as he is able to produce knives from his body and is shown to have a desire only to cut things and cause pain.

Phantom Blood
Jack the Ripper, after killing what was presumably his last victim in reality, was selected by a then-incapacitated Dio Brando to become one of his vampire minions. Refusing at first, Jack attacked Dio, but only after seeing it didn't affect him that Jack accepted Dio's offer.

Later, he corners Jonathan Joestar, Speedwagon and William Antonio Zeppeli on a tunnel, killing their horses and hiding inside the body of one. He is eventually injured by Zeppeli when he demonstrates his ripple, but escapes to a labyrinth, intending to attack from the darkness. Jonathan Joestar, now learning how to use the ripple,  is able to eliminate Jack without dropping the wine of his glass, a task given to him by Zeppeli.