Lili Quan: China-born California physician, who travels to China, by Deborah and Joel Shlian

Russell Quant: ex-farmboy, half-Ukrainian, half-Irish, gay private detective, in Saskatoon, Saskatchewan, Canada, by Anthony Bidulka

Douglas Quantrill: detective chief inspector, and Hilary Lloyd, a police sergeant, in East Anglia, England, by Sheila Radley

Francis Quarles: by Julian Symons

Quarry: psychotic Vietnam vet and hired killer in Iowa, by Max Allan Collins

Everard Peter Quayle: part of a top-secret British counter-intelligence unit working against Nazi agents, by Peter Cheyney

Ian Quayle: handsome gentleman and scholar, by Alan Caillou

Ellery Queen: author in Manhattan, New York, by Ellery Queen

Alice Quentin: psychologist in London, England, by Kate Rhodes

Philip Quest: photographer and amateur sleuth, in Spain, Sardinia, and Corsica, by Peter Townend

Faye Quick: private investigator in 1940s New York City, by Sandra Scoppettone

Ellie Quicke: 50-ish widow and amateur sleuth, in the suburbs of London, England, by Veronica Heley

Ariel Quigley: college English teacher with psychic powers, in Alexandria, Virginia, by Honora Finkelstein and Susan Smily

Sarah Quilliam: an inn owner, and Meg Quilliam, a chef, in Hemlock Falls, New York, by Claudia Bishop

Quiller: agent for a British intelligence agency so secret it has no name, by Adam Hall

Fritillary “Tilly” Quilter: arson investigator, and Isaac “Ike” Blessing, a private detective, in New York City, by Shelly Reuben

Jeb Quinlin: homicide investigator and recovering alcoholic, in Dallas, Texas, by Howard Swindle

Miranda Quin and David Morgan, a “virtual couple” of homicide detectives, in Toronto, Ontario, Canada, by John Moss

John Quincannon: 19th century private eye in San Francisco, California, by Bill Pronzini

Quinn: ex-cop turned private investigator, in Spokane and Seattle, Washington, by Anne Argula

Quinn: crime reporter, and John Piper, an insurance assessor, by Harry Carmichael

Clara Quinn, returning home from New York City to work in Raven's Nest Bookstore owned by her cousin Stephanie, in rural Maine, by Allison Kingsley (Kate Kingsbury)

Frank Quinn: former NYPD homicide detective, in New York City, by John Lutz

Garner Quinn: best-selling true crime writer, in Spring Lake, New Jersey, by Jane Waterhouse

Jericho Quinn: special agent working for a secret agency combatting international terrorism, by Marc Cameron

Joe Quinn: a cop in 1929 New York City, and an ex-cop in Cairo, Egypt in 1942, by Tom Bradby

Jonathan Quinn: ex-cop freelancing for the Office, a secret US intelligence agency, by Brett Battles

Nina Quinn: owner of Taken By Surprise, a landscaping firm specializing in surprise garden makeovers, in Ohio, by Heather Webber

Rupert Quinn: swashbuckling English courier in North Africa, by Alan Williams

Sarah Quinn: detective inspector in Birmingham, England, by Maureen Carter

Silas “Quick-fire” Quinn: Detective Inspector in charge of the Special Crimes Unit of Scotland Yard, beginning in 1914, by R.N. Morris

Terry Quinn: white and barely holding on, and Derek Strange, black and successful, ex-cops turned private investigators, in Washington, DC, by George P. Pelecanos

Carroll Quint: entertainment critic for a newspaper in San Francisco, California, by Jerry Kennealy

Hugh Quint: ex-cop private investigator in New Hampshire, by Steve Sherman

Quirke: coroner in 1950s Dublin, Ireland, by Benjamin Black (John Banville)

Julian Quist: public relations genius, by Hugh Pentecost (Judson Philips)

Septimus Severus Quistus Quistus: Roman adventurer in the first century, in the time of Nero, by Philip Boast

Imogen Quy: nurse in St. Agatha’s College, in Cambridge, England, by Jill Paton Walsh

Jim Qwilleran: journalist, with cats Koko and Yum Yum in Pickax, northeast central United States, by Lilian Jackson Braun