Series co-creator David Hoberman says that he based Monk partly on himself, and also on other fictional detectives, such as Lt. Columbo, Hercule Poirot and Sherlock Holmes. Other actors considered for the role included Dave Foley, John Ritter, Henry Winkler, Stanley Tucci, Alfred Molina and Michael Richards. The network eventually chose Shalhoub because they felt he could "bring the humor and passion of Monk to life". Stanley Tucci and Alfred Molina had guest appearances on Monk, with Tucci appearing in season 5 episode "Mr. Monk and the Actor", and Molina appearing in season 6 episode "Mr. Monk and the Naked Man".
Both Monk and Shalhoub have garnered many accolades. Monk was included in Bravo's list of The 100 Greatest Television Characters of All Time, and Shalhoub has won various awards for his portrayal, including a Golden Globe Award, three Primetime Emmy Awards and two Screen Actors Guild Awards.
Monk was originally envisioned as a "more goofy and physical" Inspector Clouseau type of character. However, co-creator David Hoberman came up with the idea of a detective with obsessive–compulsive disorder. This was inspired by his own bout with self-diagnosed obsessive–compulsive disorder; in a Pittsburgh Post-Gazette interview, he stated that, "Like Monk, I couldn't walk on cracks and had to touch poles. I have no idea why—but if I didn't do these things, something terrible would happen."
Other fictional inspirations include Columbo and Sherlock Holmes, and his obsession with neatness and order may be an homage to Hercule Poirot. Like Holmes, and occasionally Poirot, Monk is accompanied by an earnest assistant with little or no detective ability, similar to Doctor Watson and Captain Hastings, respectively; Monk's two major allies from the police department, Captain Stottlemeyer and Lieutenant Disher (credited as "Deacon" in the pilot episode), are reminiscent of Inspector Lestrade and Chief Inspector Japp, Holmes's and Poirot's well-meaning but ineffectual respective police counterparts. In addition, Monk has a brother whose abilities of deduction are even more amazing than his, yet much more geographically limited due to his own personal problems, somewhat in the style of Mycroft Holmes (who is more adept than Sherlock but also notoriously lazy).
When trying to think of a possible name for the character, co-creator Andy Breckman decided to look for a "simple monosyllabic last name"