Out of all the Elseworlds tales starring Batman, none have garnered more of a fan following than the incredibly unique Batman: Red Rain, by Doug Moench and Kelley Jones.
The first of a vampire trilogy, Red Rain is undoubtedly one of the more fun Batman tales out there. In the story, Batman is pit against Dracula, who after growing tired of keeping his identity hidden, has chosen to become the aggressor and strike terror into the hearts of mankind.
Over the course of this story, Batman gets bitten by a vampire, acquiring the necessary strength and speed to hunt Dracula and his minions. He lures them into the Batcave where he detonates multiple explosive charges, killing them. Batman then confronts Dracula and impales him, costing Batman his humanity. Now a full fledged vampire, Batman assures Alfred he has nothing to fear. Bruce Wayne may be gone, but Batman will go on forever. This wasn’t a spoiler because there’s so much more to this story.
What’s so engaging about this story is there are no villains from Batman’s usual line up taking up space. -- it's just Batman versus a Vampire army. What more do you need?