Who would win, Alucard (Hellsing Ultimate) vs Jotaro Kujo (JoJo's Bizarre Adventure)

Alucard is a vampire and a powerful warrior, with the ability to transform into a bat, a wolf, and a mist. He is also immortal and can only be killed by a specific set of circumstances. Alucard is incredibly strong and fast and has the ability to regenerate from injuries. He also wields a variety of weapons, including a pair of pistols and a sword.

Jotaro Kujo, on the other hand, has the ability to "stand" - a manifestation of his fighting spirit that allows him to summon a powerful being that can physically enhance his abilities, he also has good strength, speed, and durability but also has a good knowledge of martial arts. His stand Star Platinum has incredible speed and precision that allows him to catch bullets and move faster than the human eye can see.

Given these abilities, it would likely be a very close and intense battle, with both characters putting up a strong fight. It's possible that Alucard's immortality could give him an advantage in the long run, but Jotaro's Stand abilities may be enough to overcome Alucard's regenerative abilities.

In the end, it's hard to say who would come out victorious in a fight between these two powerful characters as it's a fan fiction matchup, not official from any manga or anime.