Down these mean streets a man must go who is not himself mean, who is neither tarnished nor afraid. The detective must be a complete man and a common man and yet an unusual man. He must be, to use a rather weathered phrase, a man of honor. He talks as the man of his age talks, that is, with rude wit, a lively sense of the grotesque, a disgust for sham, and a contempt for pettiness.
Detective Conan Kogoro Mouri, Heiji, and main character Conan Edogawa/Shinichi Kudo. In fact, Kogoro has often been shown to do stuff that people usually hire private detectives for - tracking people suspected of adultery, trying to track down someone who is lost (but not officially considered a missing person, like deadbeat dads or former friends).
One of them in Japan Inc finds out that a big union boss is a customer in an S&M club.
Heironymous "Hip" Flask is a private eye and anthropomorphic hippo in the Elephantmen comics.
From E-Man comes Michael Mauser. Just... don't call him Mickey.
Judge Dredd spinoff The Simping Detective features Jack Point, a judge working undercover as a private detective. In clown gear. Simping is a fashion trend/sub-culture in Mega City One. The point of the trend is to look as stupid as possible so that people will bother to notice that you exist.
Dwight from Sin City. His career comes to an end once he's wanted for murder, however.
In the Sam & Max universe, the main characters are rather atypical private detectives (though they prefer the term "freelance police"), while their neighbor Flint Paper is a more stereotypical, two-fisted, Dirty Harry type.
Ms Tree: She and her husband owned a private detection firm; she's carried on since his death.
A 1975 film The Black Bird is a comedy sequel to The Maltese Falcon with George Segal playing Sam Spade, Jr.
Casey Affleck's character in Gone Baby Gone is an example of a modern PI.
Kiss Kiss Bang Bang has fun with all the Film Noir tropes, this one included: Val Kilmer's character 'Gay' Perry Van Shrike is a hard-bitten, tough-talking, gun-slinging Private Detective who's also, well... gay. And considers his job very boring. And, at least until Harry and Harmony come into his life, isn't exactly dogged in his pursuit of justice.
In Lethal Weapon 4, Leo Getz becomes a licensed PI. This garners much comedy for Riggs and Murtaugh.
Riggs: Excuse me, private investigator? Could you investigate my privates?
Shaft: Who's the black private dick, that's a sex machine to all the chicks?
In The Big Fix, Richard Dreyfuss plays the most true to life private detective ever filmed. Like real private detectives, he spends most of his time on divorce cases and (mostly legal) corporate espionage and commercial investigations. For the movie he does deal with a murder, but there is no doubt it's the first one he's come across in years of detective work.
In keeping with its inspiration from classical noir, Angel Heart centres around a classical private detective, though he doesn't wear the suit and fedora as much as some of the others on this list. Unfortunately, the things he ends up dealing with are probably a heck of a lot more horrific than the other people on this list.
In Theres Something About Mary Matt Dillon plays Pat Healy, a modern day private detective who is hired to stalk on the title character for a ex-lover in high school. Pat averts the honorable portion of the trope by going after Mary for himself.
Pain and Gain: Ed Du Bois, who got out of retirement, because he liked doing that far more than fishing and golf.
Rock Slyde is a Film Noir detective parody; from having a decanter of mouthwash on his desk, to using online auction feedback to boost his self-esteem. He still narrates in a serious tone of voice.
Older Than Radio: Sherlock Holmes is often described as the 'first consulting detective.' Private detectives existed prior to Holmes, but he claimed that being a 'consulting detective' was something different:
'Well, I have a trade of my own. I suppose I am the only one in the world. I'm a consulting detective, if you can understand what that is. Here in London we have lots of government detectives and lots of private ones. When these fellows are at fault, they come to me, and I manage to put them on the right scent. They lay all the evidence before me, and I am generally able, by the help of my knowledge of the history of crime, to set them straight.'
Joe Sixsmith, a character of crime fiction author Reginald Hill, subverts most of the basic Private Detective characteristics: a short, balding, middle-aged, black private eye from Luton, whose hobbies include singing in a choir and motor mechanics. His main talents are being a nice, sympathetic sort of guy, knowing when he doesn't know things, and tremendous serendipity.
Robert B. Parker's Spenser is a modern, politically correct version of the type. If anything, he errs as far on the "sensitive" side of the "sensitive tough" archetype as Mike Hammer errs on the "tough" side.
The titular character of the Joe Copp series, written by Don Pendleton (also the author of The Executioner series), is a private detective who used to be a cop.
Mma Precious Ramotswe (in the The No. 1 Ladies' Detective Agency series by Alexander McCall Smith) subverts almost all of this trope, being a kind and overweight Botswanan lady who solves everyday problems, like absconding husbands, by a sharp psychological perception, persistence and being able to win the confidence of others.
Nohar Rajasthan from S. Andrew Swann's Moreau Series of books is a down-on-his-luck PI... who just happens to be an 8'-tall humanoid tiger Super Soldier.
In L. Jagi Lamplighter's Prospero's Daughter trilogy, Mab's body was modeled after Bogart, and he acts as the company detective.
Rex Stout's Nero Wolfe was a somewhat sedentary stay-at-home version of this; narrator Archie Goodwin did most of the legwork, and if they needed more legs they'd hire three other private investigators.
In the children's mystery series, Trixie Belden, the title character and her bestfriend, Honey, plan on opening the Belden-Wheeler Detective Agency when they're older.
Helen Walsh in The Mystery Of Mercy Close is one as well as a Defective Detective in that she's severely depressed but still does her job anyway. It's mentioned by her sisters that Helen went through a variety of jobs before settling into her career as a private detective.
In Wen Spencer's Ukiah Oregon series Max Bennett runs the Bennett Detective Agency, which he created mostly to give him a justification to look for missing persons in memory of his dead wife. Ukiah is also a licensed PI, as is Bennett's later love interest Sam Killington.
Kate Shugak is the private detective heroine of an Alaskan mystery series by Dana Stabenow.
Joe Lassiter, the protaganist of The Genesis Code, is a private investigator who runs a company that does investigation work for the wealthy and powerful elite.
Angel started out as a private detective, before he made the transition from "supernatural crime" to "supernatural". The trope is subverted in that Angel and his True Companions are better at fighting demons, and sometimes have to hire a real PI when actual investigating is required.
Humorously parodied in the Canadian TV series Butch Patterson: Private Dick. Butch is given to internal monologues, wears a fedora everywhere he goes, refers to himself as a "Dick", and drinks very heavily...so heavily, in fact, that he's known to continually wet his pants and prematurely ejaculate. To make matters worse, he's also got a thing for prostitutes, a tendency to wake up in strange places after passing out drunk, and it's unlikely he'll ever live down that incident at the petting zoo. In spite of this, he's actually a very competent detective, and generally manages to solve the case, although he quickly blows whatever money he makes on pornography and whores.
Shotaro Hidari of Kamen Rider Double is a Private Detective. However he isn't as hardboiled as he likes to think he is, leading to his fellows referring to him as "half-boiled". Both major characters refer to themselves as "two detectives in one": Shotaro does the field investigations while his partner Philip (named after Philip Marlow) does the research back home. Prior to the two meeting Shotaro worked for another, much more hard-boiled detective whose death helps to kick off the events of the series.
Emerson Cod from Pushing Daisies. He would like nothing better than to be able to just have Ned get the pertinent facts from a corpse, and then collect the rewards in short-order, with as little effort for him as possible. He also primarily deals in cases where the death has been written off as an accident or the police themselves offer a reward for any valuable information related to a case.
Gossip Girls Chuck Bass has one on speed dial. And that's not his only private investigator. His father also had a couple.
This is a decent description of Michael Westen from Burn Notice when he's working for his Client of the Week. He's even used private eye as a cover ID at least once, though on another occasion he notes that a PI license has privacy concerns (anything they uncover could end up in court).
Adrian Monk of Monk used to be police detective, but after his wife's murder he resigned and became a private detective that helps the police.
The title of Psych refers to the name of the "private, physic detective agency" main characters Shawn and Gus run. They often get hired as offical police consultants as well, however.
Yours Truly,Johnny Dollar
Richard Diamond,Private Detective
In a homage to classical noir, Dino Attack RPG brought in a Private Detective actually named Bogart when it became clear that an unknown figure was conducting a series of murders.
Private Investigations by Mark Knopfler of Dire Straits.
Ace Harding in Déjà Vu, although the games involve getting yourself out of trouble, and not solving any cases for profit.
Lewton, in Discworld Noir, both embodies and parodies this trope, due to the Disc's Theory of Narrative Causality; he doesn't know why being a private investigator means he has to wear a trenchcoat and fedora, but he's quite sure it does.
Attention-seeking "Ace Detective" Luke Atmey in Ace Attorney, who is always just a step behind Phantom Thief Mask*DeMasque. Step ahead, actually. He's the one planning the heists and sending the thief the plans anonymously, so he both gets the items and makes himself look good.
Despite being a defense attorney, Gregory Edgeworth is dressed like a stereotypical private detective in Ace Attorney Investigations 2.
Johnny Garland is one in Shadow Hearts From the New World. Surprisingly; he implies that a lot of the cases are simply helping someone track down missing pets, and takes a case offered by Gilbert simply because he wants more excitement in his life.
Reality On The Norm has the recurring character Max Griff, who styles himself as a classic Noir private eye and has constant financial problems.
In the online game Sleuth, you create and play one who can have a background you either design from the ground up, or you can choose preset backgrounds including an ex-detective disillusioned by the corruption in the system, a freelance reporter, a retired lawyer, or a reformed burglar, among others. Naturally, which background you pick affects which skills you begin with and how you approach the game.
Decoder Ring Theatre's Black Jack Justice is played straight, although there are two detectives, one male (Jack Justice) and one female (Trixie Dixon, Girl Detective), who take turns providing monologue.