Batman and Dracula: Red Rain
After discovering that the fabled vampire, Dracula, was still alive and well in Gotham City, Batman realized that recent strange dreams were the result of him being visited by Tanya, a rogue vampire who managed to break free from Dracula's control. With Tanya biting him without actually draining blood, she had infused him with the powers of a vampire without destroying his humanity. Now possessing the power to kill Dracula, Batman and Tanya lured Dracula's minions into the Batcave, where Batman destroyed the roof of the cave to expose all of the vampires to sunlight, Tanya and her followers sacrificed themselves to decimate Dracula's ranks.
With most of the vampires destroyed, Batman confronted Dracula and killed him by impaling the ancient vampire on a tree that was destroyed by lightning. However, the victory came at a cost - during the fight, Dracula successfully drained the last of Batman's blood, destroying his humanity. Nonetheless, Batman retained his sense of self and assured Alfred that only Bruce Wayne has died; the Batman will live on, and thanks to his new vampiric powers, he would be able to protect Gotham City forever.