When it comes to the smartest TV detectives we’ve ever seen, Adrian Monk definitely can count himself among them – right next to Columbo, Sherlock Holmes, and Luther (to name a few). For eight seasons of the USA Network series, Adrian Monk’s tendency to see all the details, often tied with his OCD, matched with his personal motivation to get “the guy” following the death of his wife, Trudy, was exciting to tune into week-to-week. All the while, major actors would often guest star. Some of which were big names before Monk, and others that have since skyrocketed into fame.
Jeffrey Dean Morgan
Over a decade before Jeffrey Dean Morgan became The Walking Dead’s Negan, the famed TV actor was in the Season 3 premiere of Monk, “Mr. Monk Takes Manhattan.” In the episode, Monk travels with the SFPD team to New York City to do some work in association with the murder of Trudy, but in the meantime, Monk gets embroiled in the case of a recently deceased Latvian ambassador. Morgan’s character catches the detective’s eye in connection to the ambassador’s death.
Malcolm McDowell
The lead of Stanley Kubrick’s masterful A Clockwork Orange, Malcolm McDowell, made his way into Monk during Season 4 in a particularly great episode of the series that takes the detective into the world of fashion. In “Mr. Monk Goes To A Fashion Show,” he decides to pay a visit to the inspector of his favorite collared shirts when he notices recent inconsistencies. It leads him and Natalie to meet a British fashion designer named Julian Hodge, played by McDowell.
Jennifer Lawrence
Did you know that Silver Linings Playbook Oscar winner, Jennifer Lawrence, was in Monk? Back in 2006, when the actress was a teenager and had not yet starred in any movies, she had a very small role as a high school mascot in the Season 5 episode “Mr. Monk and the Big Game.” Her head is covered for most of her scene, but she does take off the helmet for a moment in the episode.
Jason Alexander
Seinfeld’s Jason Alexander guest starred in Monk for the Season 4 premiere “Mr. Monk and the Other Detective” as another P.I. in town named Marty Eels. During Monk’s latest case, the detective begins to be overshadowed by Alexander’s character, which hilariously has Monk calling him a cheater. As Eels becomes a big competitor for Monk, it’s a blast to see Shalhoub and Alexander act together.
John Turturro
Monk perfectly cast the detective’s brother in 2004 by bringing in John Turturro in a fabulous guest role, that he would play in three episodes. Turturro, who is famous for being in movies with the Coen Brothers, Spike Lee and Adam Sandler played Ambrose, who suffers from severe agoraphobia and deepened Monk’s backstory. He was so memorable in the series that he earned an Emmy for “Outstanding Guest Actor in a Comedy Series” for the episode in which he debuted the character, in Season 2’s “Mr. Monk and the Three Pies”.
Stanley Tucci
One of the strongest Monk episodes of the series is definitely Season 5’s “Mr. Monk and the Actor.” In the 2006 episode, an actor named David Ruskin is set to play Adrian Monk in a movie based on his life and comes to shadow Adrian on his cases. Stanley Tucci plays Ruskin as the actor goes a bit too method with the role of Adrian and debunks some demons regarding what it’s like to be Monk. Tucci won an Emmy for the guest role, and was actually a finalist to play Adrian Monk prior to his guest role.
Rainn Wilson
Just a couple years before Rainn Wilson would become Dwight Schrute on one of the best sitcoms of all time, The Office, the actor made a small guest appearance on Monk in Season 2. He played a massive baseball fan and collector as Adrian Monk looked into a case involving a star baseball player.
James Brolin
Longtime TV and movie actor James Brolin (who is also the father of Josh Brolin and husband to Barbara Streisand), made his way into Monk for 2005’s Vegas episode. Brolin plays a millionaire casino owner who becomes a suspect following the death of his wife, and Stottlemeyer brings in Monk to solve the case.
Sean Astin
In Season 5, Lord of the Rings and The Goonies actor, Sean Astin crossed paths with Tony Shalhoub’s Monk in an episode called “Mr. Monk Is At Your Service.” Astin plays a young billionaire, Paul Buchanan, whom Monk and Natalie come across amidst a visit to Natalie’s parents' wealthy neighborhood. Monk ends up going undercover as Paul’s butler to learn more about him.
Sarah Silverman
Famed standup comedian, Sarah Silverman, guest starred in three episodes of Monk over the years as a character named Marci Maven. She first became part of the procedural in 2004 for “Mr. Monk and the TV Star,” where she played an obsessed fan of the star of a hit show made up for the series called Crime Lab S.F.
Danny Trejo
In “Mr. Monk Goes To Jail” in Season 2, Danny Trejo, of Spy Kids, From Dusk Till Dawn and Desperado (among many of his movies), also got to work alongside Tony Shalhoub’s Monk. During the episode, Monk goes undercover as the cellmate of Trejo’s character, who is a convicted quadruple murderer. As you may suspect, comedy ensues.
Snoop Dogg
Snoop Dogg was also in Monk for the Season’s “Mr. Monk and the Rapper,” where he played a fictional hip hop star, Murderuss. In the episode, Murderuss approaches the detective to hire him to clear his name after becoming the primary suspect in the death of another rapper. The best part? Snoop Dogg actually raps Monk’s famous “here’s what happened” segment at the end.
Alfred Molina
Beloved character actor, Alfred Molina, has also been part of Monk for a Season 6 episode. What’s interesting about Molina, is he was actually one of the finalists to play the lead role of Adrian Monk before Shalhoub was cast. In his guest role, he played a billionaire software mogul whose beach house has a view of a nudist beach.
Jon Favreau
MCU actor and famed director Jon Favreau was in “Mr. Monk Goes To The Dentist,” which aired during the series’ fourth season in 2006. Favreau plays a dentist who Lieutenant Disher goes to and swears murdered someone while he was under anesthesia for a procedure.
Carmen Electra
All-star actor, model and singer Carmen Electra can be found in the Monk episode “Mr. Monk and the Panic Room” which came out in 2004. The episode has the detective investigating a crime scene where it seems like a chimpanzee has killed his owner. The victim is a record producer and Electra plays his pop star wife.
Craig T. Nelson
Poltergeist and Parenthood actor Craig T. Nelson earned a very important role in Monk for its two-part finale, “Mr. Monk and the End.” He plays Judge Ethan Rickover, who was on the California Court of Appeals and has a history with Monk’s late wife, Trudy.
Tim Curry
In Season 1, an enemy of Monk’s was introduced as financier Dale “The Whale” Biederbeck. After the character was originated by Adam Arkin, none other than The Rocky Horror Picture Show’s Tim Curry embodied the role for a brief time in “Mr. Monk Goes To Jail.”
Niecy Nash
Reno 911’s Niecy Nash made a guest spot in Monk in the early days for “Mr. Monk and the Girl Who Cried Wolf.” The episode follows Adrian’s first assistant Sharona as she starts to believe she’s losing her sanity when she keeps seeing a man with a screwdriver sticking out of his ear (that no one else can see). Neicy Nash plays Sharona’s friend and fellow nurse, Varla should step in to assist Monk.
Jeffrey Donovan
The star of Burn Notice, which also was on USA Network like Monk, turned up in the detective series in the episode “Mr. Monk and the Astronaut.” In the Season 4 episode, Jeffrey Donovan plays an astronaut who Monk is sure killed someone, but his alibi is airtight… considering he was in space when the murder occurred.
Laurie Metcalf
Roseanne actress Laurie Metcalf had some fun on Monk when she guest starred in the Season 4 episode “Mr. Monk Bumps His Head.” When Adrian wakes up in a small town with amnesia, Metcalf’s unhinged character uses the opportunity to convince the detective he is her husband.
Nick Offerman
Parks and Recreation’s Nick Offerman made an appearance in 2005’s “Mr. Monk and the Election” before he became famous for playing the very quotable Ron Swanson. Look out for the actor in his clean-shaven days during the Season 3 episode that has Natalie Teager running for the school board.
Jane Lynch
Before actress Jane Lynch rocked sweatsuits on Glee, she did guest for “Mr. Monk Gets Married.” In the episode, Randy Disher is concerned about his mother getting suddenly married to a man who is 30 years younger (played by Lost’s Nestor Carbonell) than him and asks Monk to look into it. This leads Monk and Sharona to pretend to be a married couple for a retreat that Lynch’s psychologist character is in charge of.
Amy Sedaris
The very funny Amy Sedaris was on two episodes of Monk to play Sharona’s younger sister, Gail. She first appeared in 2002’s “Mr. Monk and the Earthquake” before also being part of 2003’s “Mr. Monk Goes To The Theater.” Since she’s an actress in the series, her part in a local play that turns into a crime scene makes the second episode a particularly juicy appearance for Sedaris.
Rachel Dratch
Saturday Night Live’s Rachel Dratch found her way into Monk for “Mr. Monk and the Missing Granny.” In the 2004 episode, Dratch’s character is stressed about the kidnapping of her grandmother and offers to help reinstate Monk to the police force if he can help find her alive.
Howie Mandel
The Gremlins actor and game and competition show host played the role of Ralph Roberts in two episodes of Monk in 2008. Howie Mandel played the head of a religious cult called Siblings of the Sun in the Season 7 episodes. Mandel is a germaphobe in real life like Monk is.
Holland Taylor
Two and a Half Men actress Holland Taylor played Natalie Teager’s mother Peggy in two episodes of Monk. In the series, Peggy is a well-off woman who married into the Davenport Toothpaste business. She is part of 2005’s “Mr. Monk Goes To A Wedding” and 2007’s “Mr. Monk Is At Your Service.”
Gena Rowlands
Gena Rowlands is an Academy Award nominee who starred in movies like Woman Under The Influence and Gloria in her youth before famously playing the older version of Allie in The Notebook. In Season 7’s “Mr. Monk and the Lady Next Door,” Monk becomes friendly with Rowlands’ Marge Johnson, but suspicions about her true intentions begin to grow.
Ariel Winter
Before Ariel Winter became part of Modern Family’s Dunphy family, the actress was in Monk as an eight-year-old for “Mr. Monk and the Astronaut.” She has a small but pivotal role as the neighbor of the victim, whose place in the story leads Monk to track down the killer.
Julie Bowen
In Season 7’s “Mr. Monk and the Bully,” Julie Bowen plays a character that Adrian Monk investigates after his childhood bully comes out of the woodwork asking for help from the detective. The Truman Show’s Noah Emmerich plays her husband and Monk’s former bully. Julie Bowen is a two-time Emmy winner for her leading role in ABC’s Modern Family.
Eric Stonestreet
Modern Family’s Cameron Tucker was on Monk the same year the hit ABC comedy first arrived on network television. In “Mr. Monk and the UFO,” Eric Stonestreet plays a small role as a local mechanic named Boom-Boom whom Monk offends and ends up raising his estimate.
Sung Kang
Sung Kang, who famously played Han in the Fast and the Furious movies, also guest starred in Monk as two separate characters. First in “Mr. Monk vs. the Cobra” he plays an employee of a martial arts school they visit while investigating the death of a fictional kung fu star, Sonny Chow. Four years later, Kang stars in “Mr. Monk on Wheels” as the cousin of a criminal named John Kuramoto.
Angela Kinsey
The Office actress Angela Kinsey had a guest role in Monk as Arlene Boras for two episodes of the series. She plays an X-ray technician who was in Alfred Molina’s episode, “Mr. Monk and the Naked Man.” She reprised her role for the 100th episode of Monk as well.
