Greg Cox wrote:
There's been a number of Holmes/Dracula books, including... The Holmes-Dracula File by Fred Saberhagen,
OMG! That brings back memories!
Here's an obscure one: "The Black Castle" by Les Daniels, one of five featuring the same vampire protagonist. Never found the others,but I did this one. It's set during the Spanish Inquisition, and features a plot twist I won't go into here...
Les Daniels’ The Black Castle is a tale of a battle between brothers. It takes place in Spain, in 1496, during The Inquisition. Perception is everything. One brother, Sebastian, is seen as evil because he is a vampire, while the other, Diego, is perceived as good because he is a man of God. But the vampire only does what he has to do to in order to survive while the churchman, an Inquisitor, inflicts pain for the power it confers upon him and the pleasure it gives him. Which is the greater evil? And who will win the soul (and body) of Margarita de Mendoza, a beautiful witch. Daniels’ tightly written horror novel was nominated for a World Fantasy Award in 1979. It was the first of five World Fantasy Award nominations he has garnered to date. The Black Castle is the first of five novels about the vampire Don Sebastian de Villanueva. While perhaps moral he is an old school vampire, unlike the romantic kind that dominates so much recent fiction. Necon Ebooks will also be publishing the rest of the series.