d’ Acquin, Sir Josse: a French knight at the Hawkenly Abbey in England during the 12th century by Alys Clare

Dahlquist, Serendipity: gum-snapping 15-yr-old girl in Los Angeles, California by Dick Lochte

Daley, Mike: lawyer and ex-priest, in San Francisco, California by Sheldon Siegel

Dalgleish, Adam: published poet and Scotland Yard commander in London, England by P. D. James

Dallas, Eve: Homicide lieutenant in 21st Century New York, New York by J. D. Robb

Dalton, Smokey: an African-American unlicensed private investigator in Memphis, Tennessee by Kris Nelscott

Dalziel, Andrew: Supt., police inspector in Yorkshire, England by Reginald Hill

Damasco, Gloria: a Hispanic detective in San Francisco Bay area in California is featured in Brown Angel Mystery by Lucha Corpi

Damen, Bill: a filmmaker turned sleuth in Santa Clara, California by James Calder

Danforth, Abigail Patience: a 19th century heiress detective by Marian J. A. Jackson

Daniel Kearney Associates: auto repo and skip-tracing firm in San Francisco, California by Joe Gores

Daniel, Judah: a freedwoman who is also the local herbalist at the time of the Civil War in Virginia by Ann McMillan

Daniel, Louisa: a sixtyish social worker by Malinda M. Hall

Daniels, Charmian: police detective in Deerham Hills, England by Jennie Melville

Daniels, Lt. Jacqueline “Jack”: works Violent Crimes in Chicago, Illinois by J. A. Konrath

Dann, Peaches: an absent-minded 50-something widow in North Carolina by Elizabeth Daniels Squire

Dansoir, Dick: a gay personal trainer and occasional go-go dancer at the boys' bars in New Orleans, Louisiana by Greg Herren

Dante, Joe: maverick cop in New York, New York by Christopher Newman

Danton, Michel: a police detective in the south of France by Norman Bogner

Darcy, Fitzwilliam: takes up the story ended in Jane Austen's Pride and Prejudice in Regency (early 1800s) England by Carrie Bebris

Draqual, Stud: (maybe gay/maybe not gay) CEO of Draqual Fashions, and a much-in-demand New York City haute-couture fashion designer of ladies’ silk underwear by William Maltese

Darcy, Tess: bed-and-breakfast owner in Victoria Springs, Missouri in the Iris House mysteries by Jean Hager

Darling, : investigator in  Broward's Rock, South Carolina by Carolyn G. Hart

da Rocca, Sigismondo: Italian agent of a Renaissance duke by Susannah Stacey

Da Silva, Jan: lounge singer and private detective in Seattle Washington by K. K. Beck

da Silva, Captain Jose: supercop in Rio de Janeiro, Brazil by Robert L. Fish

Dave, ex-cop investigator in Mesa Grande, Colorado by James Yaffee

Davecki, Alphonse “Dave”: a police detective in Superior, Wisconsin by Mike Savage

Davenport, Lucas: police detective and war games designer in Minneapolis, Minnesota by John Sandford

Davies, John: by Margot Bennett 

Davie, Dr. R. V.: of St. Nicholas College, Cambridge, England by V. C. Clinton-Baddeley

Davies, Rebecca: a child of privilege runs a home for desperate women by Troy Soos

Davilov, Queenie: a struggling screenwriter and investigator in Hollywood, California by Denise Osborne

DaVito, Angie: TV soap opera producer in New York by Louise Shaffer

Dawlish, Patrick: works with British Intelligence and later, Scotland Yard by John Creasey

Day, Jane: newspaper reporter in Washington D. C. by Ron Nessen and Johanna Neuman

Deal, John: building contractor in Miami, Florida by Les Standiford

Dean, Sam: a Jamaica-born black journalist in London, England by Mike Phillips

Deane, Sarah: a graduate student in Maine by J. S. Borthwick

Decker, Peter: LAPD detective in Los Angeles, California by Faye Kellerman

De Clerq, Robert: a member of the Special X department of the Royal Canadian Mounted Police in Vancouver, British Columbia, Canada by Michael Slade

Mr. Dee: an Englishman in England by Desmond Cory

Dee, Judge: Chinese magistrate in the 600s by Robert Van Gulik

Deean, Catherine “Cat'”: part-owner of a catering enterprise in Los Angeles, California by Cynthia Lawrence

Deene, Carolus: an ex-commando turned schoolmaster in England by Leo Bruce

Deer, Howard Moon: a private investigator in San Geronimo, New Mexico by Robert Westbrook

de Gier: police detective in Amsterdam, Netherlands by Janwillem Van de Wetering

DeGraaf, Dr. Gerritt: forensic pathologist in Chicago, Illinois by Barbara D'Amato

Delafield, Kate: a lesbian homicide detective in Los Angeles, California by Katherine V. Forrest

Delaney, Edward X. “Iron Balls”: retired chief of detectives in New York, New York by Lawrence Sanders

Delaney, McLeod: a Pulitzer-Prize-winning journalist from Florida, comes to Princeton University as a visiting lecturer, later professor, in Princeton, New Jersey by Ann Waldron

Delaney, Patricia: a private investigator in Cincinnati, Ohio by Sharon Gwyn Short

Delaney, Sarah Booth: unconventional Southern Belle in Zinnia, Mississippi by Carolyn Haines

Delaware, Alex: child psychologist in Los Angeles, California by Jonathan Kellerman

DeLeeuw, Kit: Wall Street shark turned suburban detective in Rochambeau, New Jersey by Jon Katz

Delchard, Ralph: soldier in 11th century England by Edward Marston

Delmas, Jack: a private investigator from the Mississippi Gulf Coast by Martin Hegwood

Delvecchio, Nick: private eye in Brooklyn, New York by Robert J. Randisi

Demarkian, Gregor: former FBI department head in Philadelphia, Pennsylvania by Jane Haddam

DeMarco, Johnny: after 5 years as a PI wins a comeback fight at age 40 in Brooklyn, New York Frank Megna

Dempsey, Mary Teresa: 5'2" 200 lb. nun in Chicago, Illinois by Ralph M. McInerny

Denison, Skye: a school psychologist in Scumble River, Illinois by Denise Swanson

Denson, John: an ex-reporter and ex-army intelligence operative acts like a flaky private investigator in Seattle, Washington by Richard Hoyt

Denton, Harry James: ex-newspaper reporter turned private investigator in Nashville, Tennessee by Steve Womack

Department Z: chronicles the tales of British espionage by John Creasey

de Quincy, Justin: bastard son of a bishop in 12th century England by Sharon Kay Penman

Devereaux: aka The November Man, a field intelligence agent for R Section in New York, New York by Bill Granger

Devilin, Fever: a folklorist and native of the Georgia Appalachians by Phillip DePoy

Devine, Jude: a lesbian ex-FBI agent, now a Montezuma County Sheriff’s detective in Utah by Rose Beecham

Devlin, Harry: a solicitor in Liverpool, England by Martin Edwards

Devlin, Jack: ex-Secret Service turned security firm investigator  the U.S.A. by John Clarkson

Devlin, Liam: 1940s IRA hero in Ireland by Jack Higgins

Devlin, Matt: private eye in 1890s Newport, Rhode Island by Mary Kruger

Devlin, Mike: FBI agent in Detroit, Michigan by Paul Lindsay

Devlin, Paul: NYPD detective in New York, New York by William Heffernan

Devonshire, Betsy: needlework shop owner in Excelsior, Minnesota by Monica Ferris

Dewitt, Holly: a film producer and single mother in Miami, Florida by Sherryl Woods

de Wolfe, Sir John: the crowner (coroner) in 12th century Devon, England by Bernard Knight

Diamond, Eve: a reporter for the LA Times, in Los Angeles, California by Denise Hamilton

Diamond, Jake: a private investigator who is more over-easy than hard-boiled, in San Francisco, California by J. L. Abramo

Diamond, Peter: ex-cop in Bath, England by Peter Lovesey

Diamond, Venus: U.S. Fish & Wildlife agent in Washington State by Skye Kathleen Moody

Diavolo, Dan by Stuart Towne

Dickens, Charles: a 19th century writer in London, England by  William J. Palmer

Didier, Auguste: Master Chef in Victorian London, England by Amy Myers

Di Ganzarello, Alessandro: part of a James Bond-like trio in London, England by Ivor Drummond

Dillman, George Porter: a yacht-builder, turned actor, turned detective by Conrad Allen

Dillon, Sean: IRA enforcer turned British special agent in Ireland by Jack Higgins

Di Marco, Jeff: insurance investigator in Boston, Massachusetts by Doris Miles Disney

Dimity, Aunt: a romantic ghost in England by Nancy Atherton

Di Palma, Laura: attorney in San Francisco, California by Lia Matera

Dobbs, Maisie, a psychologist and investigator in 1929 England by Jacqueline Winspear

Dobie, John: a Professor of Mathematics in Cardiff, Wales by Desmond Cory

Dodge, Lark: a bookseller in Washington State by Sheila Simonson

Dolan, Trixie: an actress in London, England by Marian Babson

Donaghue, Ulysses Finnegan: a Shakespeare scholar private eye in Provence, France by Anna Shone

Donahoe, Neal: Harbor Patrol Officer  in Santa Barbara, California by Tony Gibbs

Donovan: Danny Coyle's assistant by Judson Philips

Donovan, Bill: Chief of Special Investigations, New York, New York by Michael Jahn

Donovan, Cal: a cop in Castlemer, England by Jo Bannister

Donovan, Jack: an FBI profiler by John E. Douglas

Doolittle, Delilah: a British widow and pet detective and her Doberman pinscher named Watson in Surf City, California by Patricia Guiver

Dorsey, Carroll: private investigator in Pittsburgh, Pennsylvania by Thomas Lipinski

Dortmunder, John: comic thief in New York, New York by Donald E. Westlake

Dougal, William: post-grad student and security firm employee in England by Andrew Taylor

Dover, Wilfred: a fat lout of a Chief Inspector in England by Joyce Porter

Dowling, Father Roger: St. Hilary's parish priest in Fox River Illinois by Ralph M. McInerny

Doyle, Arthur: a young doctor in Edinburgh, Scotland by David Pirie

Doyle, Conan: 19th century writer in London, England by Walter Satterthwait

Doyle, Molly: an antiques dealer in Carmel, California by Elaine Flinn

Drake, Jessie: a homicide detective in Los Angeles, California by Rochelle Krich

Drake, Stephen: a newspaper reporter with ESP in San Francisco, California by Collin Wilcox

Dresden, Harry: the only wizard listed in yellow pages in Chicago, Illinois by Jim Butcher

Drexler, Sarah: a judge in Oregon by Kate Wilhelm

Driscoll, Clifford no-name American spy in New York, New York by William L. DeAndrea

Drover, Jimmy: ex-sportswriter in Chicago, Illinois by Bill Granger

Major Drummond, Sean “Bulldog”: a lawyer in the army’s Judge Advocate General's Corps (JAG) by Brian Haig

Dubonnet, Tubby: a lawyer in New Orleans, Louisiana by Tony Dunbar

Duff, MacDougal: a retired history professor in New York, New York by Charlotte Armstrong

Duffy, Nick: a bisexual ex-cop turned private investigator in London, England by Dan Kavanagh

Dugan, a lawyer in Chicago, Illinois by David J. Walker

Duncan, Eve: forensic sculptor by Iris Johansen

Dunlop, Luke: an agent for the Witness Protection Agency in Australia by Peter Corris

Dunn, Micah: a private investigator in New Orleans, Louisiana by M. K. Shuman

Dunne, Fintan: a hard-boiled detective in pre World War II New York, New York by Peter Quinn

Dupin, C. Auguste: a detective in the first “real” detective story by Edgar Allan Poe

Du Pré, Gabriel: Métis (Cree and French, maybe a little English) cattle inspector and sometimes sheriff in Montana by Peter Bowen

M. Dupuy by Anthony Gilbert

Durant, Quincy, a soldier of fortune for the company, WuDu Ltd. by Ross Thomas

Durell, Sam: a CIA agent by Edwards S. Aarons and Will. B. Aarons

Duvall, Starletta: homicide lieutenant in Brookport, Massachusetts by Judith Smith-Levin

Dwyer, Jack: ex-cop part-time actor and security guard in Cedar Rapids, Iowa by Ed Gorman

Dye, Billy: a struggling author in Manchester, England by David Bowker

Dyer, Mandy: owner of Dyer's Cleaners in Denver, Colorado by Dolores Johnson

Dyke, Toby: a reporter in Devon, England by E. X. Ferrars

Dyson, Lindsey: an  investigative reporter by Calley Moore