The Hollows series (also called the Rachel Morgan series) is a series of mystery novels in an urban fantasy alternate history setting by Kim Harrison that take place primarily in the city of Cincinnati. The city itself is mostly separated in two parts: The main part of the town (usually called downtown) and the enclave on the opposite side of the Ohio River nicknamed "The Hollows". Most Inderlanders in Cincinnati live on "The Hollows", although exceptions exist on both sides.
The series currently consists of eight novels and five short stories published by HarperCollins Publishers.
Novels in the series are told in the first-person point-of-view of Rachel Morgan, a detective witch who works with local law enforcement agencies and faces threats both mundane and supernatural in origin. The series also focuses on Rachel's relationships with her partners, a living vampire and a pixy, as well as her personal relationships with males of different species.