- It has been suggested that Captain Holly Short of the Artemis Fowl series may not own a copy of the rule book. If she does, she has certainly never read it.
- The Black Echo by Michael Connelly - Harry Bosch is this trope to a T.
- Madeleine Urban & Abigail Roux's M/M crime romance series Cut And Run gives us FBI Special Agents Ty Grady and Zane Garrett, who are both Cowboy Cops (though Zane keeps up a By-the-Book Cop facade most of the time, in contrast to his more Hair-Trigger Temper partner).
- In The Dresden Files, Lieutenant (later Sergeant) Murphy plays this straight when she helps out Harry Dresden but is also distinctly Lawful Good, especially in the early books to Inspector Javert levels.
- Harry is effectively one of these as Warden of the Council.
- Deconstructed with Sam Vimes in Discworld. Vimes, despite being promoted time after time, is nonetheless an archetypal Cowboy Cop, rejecting the rules if they stop him from doing his job and hunting down criminals - or, as in Night Watch, rejecting the code that has lead to the Watch becoming useless and Ankh-Morpork a police state - and frequently running up against Da Chief in the form of Vetinari (although Vetinari is quite trope-savvy in this case, and appears to willingly take the position of Da Chief in order to nudge Vimes in the right direction). The deconstruction comes because Vimes hates it - he hates that the system does not work, that it forces him to be a Cowboy Cop to get things done and that it keeps trying to push him into chaos when all that is important to him is the law.
Occasionally he resorts to it and the trope is played straight. It is always in circumstances that clearly warrant extreme measures. His rationalization: "It's me doing it." Put it this way; Vimes is a Cowboy Cop who kept getting promoted. He's also very aware that the justification "It's all right to break the rules because it's me doing it" could very easily be the start of a very slippery slope.
A character that is a unmitigated Cowboy Cop, is the wali of Prince Cadram, 71-hour Ahmed. As he says to Vimes (paraphrased): "Your beat is a city you can walk across in half an hour. Mine is a million square miles of barren desert with no company but sword and camel." His rationality is that he must strike first, and swiftly, before the criminal has a chance to. He got his nickname from when he killed a man in the man's own tent after 71 hours, not the 72 mandated by Klatchian hospitality customs, because the man had poisoned a well, and he had testimony and a confession.
- When Vimes continues his Cowboy Cop ways in Night Watch, it works so well that Da Chief tries to have him assassinated. Ouch. Da Chief wasn't Vetinari this time- Vimes went back in time many years due to a magical accident and ended up as the Sergeant that trained his younger self. A young Havelock Vetinari actually saved Vimes from assassination at one point. This kind of thing happens on the Discworld all the time; apparently there's nothing that can be done about it....
- Sergeant Detritus could be considered a Cowboy Cop as well. In his case, the subversion is that he's a troll officer who usually works the troll beat, and it could be argued that in a culture who regard hitting each other with rocks as a form of conversation, nailing drug-dealers to the wall by their ears is simply maintaining community relations.
- The Godfather: Albert Neri was more than a "loose cannon" as a cop. Frustrated at the inability to do anything about the parking violations around the UN building he bashed in the ambassadors' windshields until he was reassigned to Harlem, then he smashed the skull of an unconscious pimp that he had caught molesting a little girl, which got him sent to prison. Fortunately, his father in law knew the Corleones, and Michael was looking for a replacement for Luca Brasi.
- The In Death series. Eve somehow manages to be both a By-the-Book Cop and this!
- Matthew Hawkwood - a cowboy Bow Street Runner!
- Captain Kotov in Night Watcher, at least before he became a Cowboy Vampire Hunter.
- In Ragnarok, the first of The Echo Case Files, Navarro, a local police officer, brings a SWAT team along on a Confederate Marshals operation without getting permission from his superior. Except, well, this is a subversion: he's only a maverick because he's acting like a proper police officer in a corrupt department.
- Joe Pickett in the novels by C.W. Box is a game warden with a reputation as a cowboy cop (his position does give him law enforcement powers). Joe doesn't set out to deliberately break the rules, but operating on his own a long way from any back-up means he often has to employ his own initiative. His 'cowboy ways' - along with a personality clash with his supervisor - even gets him fired at one point.
- In The First Rule Of Survival, veteran South African detective Vaugn de Vries is seen, by the new Black African leadership of the SAPS, as an anachronistic dinosaur whose attitudes and approach to policing are not only a product of The Apartheid Era, but completely out of synch with modern policing methods. Knowing his time in the South African Police Service is most likely coming to an end, he takes on a case involving child sex abuse and trafficing of abducted boys in a manner that seriously strains the rulebook, and involves a lot of cowboy coppery.