Hellsing, Majin Tantei Nougami Neuro Recommendations
Maybe the only one thing that links these series together is the main characters. Neuro and Alucard are both from Hell (in some way) and have connections with devils. Both of them have young, not very smart and quick-witted female assistants. And finally they have the same charisma, arisen from their nature.
Neuro and Yako are really similar to Alucard and Integra (when she was small of course) and Neuro's hellish powers and demeanor remind me very much of the ones of Alucard. If you like Hellsing, I'm certain you like Majin Tantei Nougami Neuro and the other way around.