He has obsessive-compulsive disorder (OCD) and multiple phobias, all of which intensified after the murder of his wife Trudy, who died in a car bomb, resulting in his suspension from the department.

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.

[2] 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.

"[3] Other fictional inspirations include Columbo[2][5][6] and Sherlock Holmes, and his obsession with neatness and order may be an homage to Hercule Poirot.

[2] 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;[7] 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' 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 notoriously lazy).

[10] USA Network's executive vice president Jeff Wachtel stated that looking for the right actor to portray Monk was "casting hell".

[10] Although Michael Richards was considered, distributors of the show ABC and Touchstone worried that the audience would typecast him for more comedic roles after his previous work as Cosmo Kramer on the sitcom series Seinfeld.

Quick, brilliant, analytical... [with] an encyclopedic knowledge of a dozen unconventional and assorted subjects, from door locks to horticulture to architecture to human psychology."

In addition, new phobias develop at seemingly random intervals, such as a temporary fear of blankets at the end of the season 5 episode "Mr. Monk Gets a New Shrink".

[16] His first assistant, Sharona Fleming (Bitty Schram), is a single mother and practical nurse by profession, hired by the police department to help Monk recover from the three-year catatonic state he lapsed into after Trudy's death.

[14] After several years of loyal service, Sharona leaves the show in season 3 to return to New Jersey and remarry her ex-husband Trevor.

[8] He has a photographic memory,[16] and can reconstruct entire crime scenes based on little more than scraps of detail that seem unimportant to his colleagues.

Another example is when entering a chaotic murder scene in the episode "Mr. Monk Meets Dale the Whale", his first impulse is to straighten the lamps, though he is frequently able to hold off his fixations when examining bodies or collecting evidence.

[24] Even though Monk's mental state in the series is said to be a result of his wife's death,[14][25] he shows signs of OCD in flashbacks dating back to childhood.

Charles Kroger (Stanley Kamel) in the first six seasons and Dr. Neven Bell (Héctor Elizondo) in the last two seasons—weekly, and at several points, daily.

One breakthrough is shown in the season 8 episode "Mr. Monk Goes to Group Therapy", when Adrian is locked in a car trunk with his fellow OCD patient and personal rival, Harold Krenshaw.

During the terrifying trip, both men overcome their longstanding claustrophobia (fear of small spaces), as well as their own differences, resulting in them becoming friends.

It is known he was born in the fictitious Marin County town of Tewksbury, to parents Agnes (Rose Abdoo) and Jack Monk, Sr (Dan Hedaya).

[19] Jack explains that he did not return to his family because the message in his fortune cookie read "Stand by your man", which he interpreted to mean that he should follow his own path.

[21] Throughout the series, Adrian mourns his wife Trudy (Melora Hardin/Stellina Rusich), who was killed on December 14, 1997, by a car bomb he believes was meant for him.

[43] Nancy Franklin of The New Yorker said that Shalhoub is "brilliant at conveying the tension between Monk’s desire to conquer his disorder and his dug-in defense of his behavior".

[50] In 2003, Shalhoub won the Golden Globe Award for Best Actor – Television Series Musical or Comedy;[51] he was nominated for the same category in 2004, 2005, 2007 and 2009.