Nameless: private eye in San Francisco, California, by Bill Pronzini

Rachel Narey: a detective sergeant, and Tony Winter, a police photographer, and others, in Glasgow, Scotland, by Craig Robertson

Joe Narrabone and Luke Pagan: metropolitan police who become British intelligence operatives, in London, England, by Michael Gilbert

Donovan Nash: pilot for hire, by Philip Donlay

E.L. Nash: police detective in Los Angeles, California, by Stephen Smoke

Karen Nash: small town librarian from Minnesota who moves to London to open a bookstore, by Mary Lou Kirwin

Mike Nash: detective inspector in Yorkshire, England, by Bill Kitson

Monty Nash: loner agent working against the Reds with the US Department of Counter Intelligence, by Richard Telfair (Richard Jessup)

Harry Nautilus and Carson Ryder, police detectives in Mobile, Alabama, by Jack Kerley

Jackson “Tres” Navarre: Tai Chi master and unlicensed private investigator, in San Antonio, Texas, by Rick Riordan

Cass “Scary” Neary: amoral speedfreak kleptomaniac murderous alcoholic bisexual heavily-tattooed American female photographer, by Elizabeth Hand

Nebraska: part-time private investigator trying to write, in Omaha, Nebraska, by William J. Reynolds

Grazia Negro: young female detective assigned to a special task force designed to catch serial killers, in Bologna, Italy, by Carlo Lucarelli

Neil, Milos, Lucio, and Ramon meet for lunch and take turns to tell their stories, in the Lunch series by Derek Hansen

Rob Neill: sheriff’s investigator, and Meg McLean, a librarian, in the Latouche County mysteries by Sheila Simonson

Gridley Nelson: rich, Princeton-educated homicide lieutenant, later captain, in New York City, by Ruth Fenisong

Harry Nelson: detective chief inspector, and Dr. Ruth Galloway, a forensic archaeologist, in the Saltmarsh area near Norfolk, England, by Elly Griffiths

Vicki Nelson: ex-cop turned private investigator with a vampire lover in Toronto, Ontario, Canada, by Tanya Huff

Nergui: ex-head of the Serious Crime Squad, in Ulan Bator, Mongolia, by Michael Walters

Eliot Ness: 1930s public safety officer in Cleveland, Ohio, by Max Allan Collins

Jimmy Nessheim: young FBI agent beginning in late 1930s Chicago, Illinois, by Andrew Rosenheim

Alice Nestleton: actress and cat-sitter in rural New York state, by Lydia Adamson

Georgiana Neverall: software engineer turned plumber, returning to her old home town of Pine Ridge, Oregon, by Christy Evans

Billy Nevers: operating in the dangerous world of high finance, high crime, and expensive women, in New York City and elsewhere, by Joseph Mark Glazner

Yuri Nevsky: information specialist in Pittsburgh, Pennsylvania, by Dimitri Gat

Chloe Newcomb: victims advocate in Cochise County, Arizona, by Beth Thornton

Bob Newman and Paula Grey: secret service agents, and Tweed, British Secret Service second in command, by Corbin Forbes

Terrell Newman: detective in San Antonio, Texas, by Bernard J. Taylor

Lucy Newroe: newspaper editor and volunteer EMT, in Santa Fe, New Mexico, by Christine Barber

Phyllis Newsom: elderly amateur sleuth and pie expert, in Weatherford, Texas, in the Fresh-Baked mysteries, by Livia J. Washburn

Thursday Next: agent of the Special Operations Network, Literary Division, in Great Britain, in a funny sci-fi, alternate history series by Jasper Fforde

Lee Nez: nightwalker (vampire) police officer in New Mexico, by Aimée and David Thurlo

Billy Nichols: boxing columnist for the Inquirer newspaper, in late 1940s San Francisco, California, by Eddie Muller

Jane Nichols: secret agent turned mystery writer, in Savannah, Georgia, by Maureen Tan

Hedley Nicholson: private investigator in England, by Mary Kelly

Constable Nick: policeman in Aidensfield, North Yorkshire, England, by Nicholas Rhea (Peter Walker)

Martha “Marty” Nickerson: prosecuting attorney, in Chatham on Cape Cod, Massachusetts, by Rose Connors

Nicolaos: investigator in classical Athens, beginning in 461 BCE, by Gary Corby

Billy Nightingale: arson investigator, and Sebastian Bly, a state trooper, by Shelly Reuben

Brett Nightingale: detective inspector (later chief inspector), in Edinburgh, Scotland, by Mary Kelly

Deirdre Quinn Nightingale: veterinarian in New York City, by Lydia Adamson

Shane Nightingale: 12-year-old orphaned in the 1906 earthquake, and Randall Blackburn, a homicide detective who adopts him, in San Francisco, California, by Anthony Flacco

Pam Nilsen: lesbian printing company owner in Seattle, Washington, by Barbara Wilson

Charlie Noble: ex-Coast Guard officer turned marine private investigator, in the West Coast series by Clyde W. Ford

Monica Noble: vicar’s wife in the Cotswold village of Heyford Bassett, England, by Joyce Cato (Faith Martin)

Parker Nobel: deputy attorney general and burned-out former prosecutor, in Iowa, by Mike Manno

Nolan: aging thief in Iowa, by Max Allan Collins

Craig Nolan, Ashlyn Hart, and Tain: police constables in Vancouver, British Columbia, Canada, by Sandra Ruttan

Wylie Nolan: arson investigator, and Max Bramble, an attorney, by Shelly Reuben

Ed Noon: private investigator in New York City, later on special assignment to the President of the United States, by Michael Avallone

Joe Noonan: ex-cop, Vietnam vet, private investigator, in New York City, by Daniel Hearn

Chris Norgren: art museum curator in Seattle, Washington, by Aaron Elkins

Jennifer Norrington, Alessandro Di Ganzarello, and Coleridge Tucker, a James Bond-like trio in London, England, by Ivor Drummond (Roger Erskine Longrigg)

Mrs. Norris: Scottish housekeeper and amateur sleuth, and Jasper Tully, a DA investigator, in New York City, by Dorothy Salisbury Davis

Lindsey Norris: director of the Briar Creek Public Library, in Briar Creek, Connecticut, in the Library Lover’s mysteries, by Jenn McKinlay

Carl North: small-town cop and amateur hockey goalie, in Belleford and then St. Thomas, Ontario, Canada, by Terry Carroll

Eddie North: police sergeant in Philadelphia, Pennsylvania, by Scott Flander

Hugh North: US Army intelligence officer, a captain at first, finally colonel, serving around the world as G-2’s greatest troubleshooter, by Van Wyck Mason

Tru North: lesbian police detective in Kansas City, Missouri, by Janet McClellan

Les Norton: nightclub bouncer in Sydney, Australia, by Robert G. Barrett

Richard Nottingham, Constable of Leeds, in 1730s England, by Chris Nickson

Jack Novak, mostly in Mexico and the Caribbean, by E. Howard Hunt

Markus Novak: private investigator working for a Florida law firm that specializes in exonerating death row inmates, by Michael Koryta

Sadie Novak: former teacher now running Scene-2-Clean, a cleaning company specializing in cleaning up death scenes, in Seattle, Washington, in the Ghost Dusters series by Wendy Roberts

Alo Nudger: private investigator in St. Louis, Missouri, by John Lutz