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

Narrabone, Joe: a WWI policeman turned British Secret agent in London, England by Michael Gilbert

Nautilus, Harry: a police detective in Alabama by Jack Kerley

Navarre, Jackson “Tres”: Tai Chi master, unlicensed P.I. in San Antonio, Texas by Rick Riordan

Nebraska: part-time PI 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

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

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

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

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

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

Newman, Bob: a British secret agent written as by Corbin Forbes

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

newsroom crew: in Minneapolis, Minnesota by Ron Handberg

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

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

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

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

Nickerson, Martha "Marty": a prosecuting attorney of Chatham on Cape Cod, Massachusetts by Rose Connors

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

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

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

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

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

Nolan: aging thief in Iowa by Max Allan Collins

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

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

Norrington, Jennifer: part of a James Bond-like trio in London, England by Ivor Drummond

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

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

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

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

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