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

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

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

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

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