Few series in the modern era of television have successfully pulled off the delicate balance that is the genre of dramedy as effortlessly as the USA Network's Psych. Featuring truly vibrant and colorful main characters, a seemingly endless supply of 1980s references, and an impressive number of tribute and parody episodes alike, Psych is truly unlike any other series. And that's saying something, for a series that relied so heavily on the familiar territory of crime procedurals.

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Along with its mile a minute delivery of jokes and its frequent references to popular and obscure 1980s music, movies, and shows; Psych also featured some truly impressive celebrity guest stars. Some of these guest stars only appeared once, but others performed on a recurring basis. Regardless of the length of their tenure, each one of these ten performers left an indelible mark on the series.

Jaleel White (Tony Clemon)

Jaleel White as Tony in Psych

Psych never shies away from exploring its main characters back stories. Arguably one of the better character moments features Burton Guster's college days and his acapella group, Blackapella. Appearing in a few episodes throughout the series, Gus's acapella brothers treat Gus like a real sibling, ribbing and judging him for almost everything.

One of the best members of this formerly tight-knit group is the no-nonsense Tony Clemon, masterfully performed by none other than Jaleel White of Steve Urkel and Family Matters fame. White appears twice in the series, lending his soulful crooning and pitch-perfect dry humor to two of the series' best crime capers.

Kenan Thompson (Joon)

Kenan Thompson as Joon in Psych

Tony may be a great member of the Blackapella group, but far and away the best member (besides Gus, of course) is Kenan Thompson's Joon. Adorably dim-witted and passionate about basically everything, Joon is the funny man to Tony's straight man. Together, the two represent their own version of the series' iconic Shawn and Gus duo.

Notable for his tenure on Nickelodeon and Saturday Night Live alike, Thompson is one of the series' most talented comedic performers with an incredibly long career. The role of Joon allows him to tap into some of his best comedic talents, including some truly hilarious physical humor and his own singing ability.

Phylicia Rashad (Winnifred Guster)

Winnie Guster smiles at her son Gus in the kitchen of the Guster home in Psych

Burton Guster is essentially the child that every parent wishes they could have. Hard working, incredibly smart, kind and trusting to a fault; Gus is about as good as it gets, in terms of television sons. It's only fitting, then, that he has one of the best mothers in sitcom history for a mother. Phylicia Rashad, famous for her tenure as Clair Huxtable on The Cosby Show, appears in a handful of episodes as Gus's mother, Winnifred Guster.

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While Winnifred may initially seem like a goody two shoes, much like her son, Rashad soon gets some truly meaty material to work with. Winnifred is accused of murdering a neighbor and also hides gambling habits and debts from her family. Despite her many vices, Winnie is an incredibly loving and protective mother. Rashad looks like she's having a ball each and every time she appears.

Curt Smith (Curt Smith)

Shawn Spencer and Burton Guster harmonize with Curt Smith of Tears for Fears as he plays guitar in Psych

Psych is truly unlike any other series of the modern era, barring Stranger Things, in its absolute love and worship of all things from the '80s. Unlike Stranger ThingsPsych is set in the present and represents an entirely different form of tribute, parody, and meta-textual reference. Countless stars of the decade appear throughout the series, but one of the most enjoyable cameos come from a member of a beloved band.

Curt Smith, one-half of the iconic Tears for Fears, appears a few times throughout the series as a heightened, satirical version of himself. He provides entertainment at the homes of both Declan Rand and Billy Lipps, winds up being shot and mauled by a panther, and gets eaten alive by zombies in a dream sequence. Smith is a good sport for enduring all the show puts him through and provides some music for the series' soundtrack.

Tony Cox (Tony Cox)

Tony Cox as himself in Psych

Psych fully embraces the trope of holiday-themed episodes, featuring multiple Christmas events in particular. The fifth season's "The Polarizing Express" goes down the Its a Wonderful Life route. In this episode, Shawn falls asleep and wonders what life would be like in Santa Barbara if he had never come home and taken up life as a psychic detective.

Rather than the angel Clarence, Shawn is led along this journey by Tony Cox of Bad Santa fame. Cox's signature sharp wit and almost abrasive delivery provides an otherwise serious and somber episode with a necessary injection of humor. Cox and James Roday's Shawn prove to be quite the hilarious comedy duo, almost to the extent that we wish Cox could have returned in some other capacity.

Jeffrey Tambor (Lloyd French)

Jeffrey Tambor as Lloyd French in Psych

Juliet's backstory is explored less than most of the series' other main characters, but one of the best choices the series ever made was to introduce the character of her father, Lloyd French. Seemingly a mild-mannered accountant, Lloyd hides a secret life of gambling and interacting with drug dealers in Mexico, a seedy adventure that he winds up pulling Henry Spencer, Shawn, and Gus into in the spirited seventh season episode "No Country For Two Old Men."

Lloyd and Henry strike up an unlikely friendship, despite how much Lloyd gets on Henry's nerves. All the while, Lloyd is an entirely winning character despite his many faults, all thanks to the charismatic performance by comedy legend Jeffrey Tambor.

Jimmi Simpson (Mary Lightly)

Jimmi Simpson as Mary Lightly in Psych

Long before he was winning hearts and then breaking them as William on Westworld, Jimmi Simpson broke out onto the acting scene with his scene-stealing turn as Psych's wonderfully quirky Mary Lightly. First introduced as a consultant on the serial killer Mr. Yang's cases, Mary is just about as weird as a character gets in the zany world of Psych. Despite every odd and occasionally off-putting trait he displays, Simpson's performance makes Mary one of the most beloved and truly endearing characters in the entire series.

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Even after being tragically killed in the series' fourth season finale, Mary continues to appear, because it would be a damn shame to waste Simpson's considerable talents and Mary's absolute charm. He's appeared in archive footage, in a dream, and even in a musical number. Every time he appears, we couldn't be happier to see him.

Ally Sheedy (Mr. Yang)

Ally Sheedy as Mr Yang in Psych

Almost every successful crime series features a nemesis for the main character. In the world of Psych, Shawn Spencer's nemesis is the nefarious and truly unhinged Mr. Yang, a female serial killer who's got a sick fixation on Shawn and his family. Played truly in an entirely serious manner, Yang would be one of the creepiest villains in television history.

Pairing this creepiness with truly over the top and dark humor, Ally Sheedy turns in the performance of a lifetime as Mr. Yang. Appearing in a handful of episodes over the course of the series, including a tribute to Hitchcock and the series' musical special, Sheedy consistently remains one of the series' strongest performers, time and again.

Tim Curry (Nigel St. Nigel)

Tim Curry as Nigel St Nigel in Psych

The second season premiere of Psych, "American Duos," is widely regarded as one of the best episodes of the series. A pitch-perfect send-up of the ridiculous hype that surrounded American Idol in the early days of the series, the episode follows Shawn and Gus as they go undercover as contestants on the series American Duos, in hopes of preventing a killer from striking again in hopes of killing their way to the winner's spot.

The episode manages to get almost everything right about American Idol, especially in its earliest days, but perhaps the best thing it does is feature Tim Curry in the role of Nigel St. Nigel. An entirely exaggerated tribute to the curmudgeonly Simon Cowell, Curry's St. Nigel is as loathsome as he is lovable, as cuddly as he is cruel, and as downright hilarious as he is deadly serious. He's one of the best characters the series ever created, and one of the best guest stars.

Cary Elwes (Pierre Despereaux)

Burton Guster, Pierre Despereaux, and Shawn Spencer stand together outside in Psych

While Mr. Yang may have been Shawn's nemesis, Pierre Despereaux was Detective Carlton Lassiter's rival. A seemingly impossible to catch art thief, Despereaux had long evaded capture, getting away with stunning and priceless works of art through sheer charm and wit. Cary Elwes, most well-known for his work in The Princess Bride (yet another 1980s reference), turns in an amazingly over the top performance as Despereaux.

Against all odds, Despereaux, Shawn, and Gus become friends, despite Despereaux's status as a world-renowned criminal. He helps out on many cases and, in his final appearance, an earth-shattering revelation is (maybe?) made about his identity. Each and every time he appears, Elwes proves that he was made for this role, and fits effortlessly into Psych's wonderfully over the top world.

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