As beloved as the Psych franchise has always been by its devoted legion of fans known as Psych-osthere's no way to ignore the fact that expectations were incredibly high for the new Peacock original film, Psych 2: Lassie Come Home. The film marked the first entry in the franchise in three years, and also the full return of Timothy Omundson as Carlton "Lassie" Lassiter after Omundson's stroke.

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Based on glowing fan responses and critical reviews alike, the film has been received as a real success, a welcome sign that there's more to be had yet from the franchise. A large part of what made the film work so well was its incredible cast of guest stars and familiar faces.

Sarah Chalke as Dolores O'Riordan

Sarah Chalke in Psych 2 Lassie Come Home

Best known for her work in the iconic sitcom Scrubs, Sarah Chalke joins yet another quirky best friend duo with her appearance in Psych 2. As Dolores O'Riordan, Lassie's nurse during his rehabilitation, Chalke is another strong addition to the series' legacy of creating unique, hilarious, slightly off characters.

But in the case of Dolores, she's more than a little bit off, as - spoiler alert - it's revealed that she is the murderous mastermind behind all of the goings on at the rehabilitation facility. Chalke doesn't quite sell this sudden turn, however, which leaves her at the end of the list.

Allison Miller as Cat Restaurant Owner

Allison Miller in Psych 2 Lassie Come Home

One of the most colorful additions to the Psych universe in this movie is Allison Miller's aptly named Cat Restaurant Owner. As the total hipster millennial renting out the former Psych office space, Cat Restaurant Owner is, well, doing just that by setting up a cat cafe for Santa Barbara's locals.

Miller, of course, is James Roday Rodriguez's love interest on their current series A Million Little Things, lending her small guest appearance a bit more of a fun touch than some others.

Kristy Swanson as Marlowe Viccellio-Lassiter

Kristy Swanson in Psych 2 Lassie Come Home

Though absent from the previous Psych film as a consequence of Timothy Omundson's overall absence, Lassiter's wife Marlowe makes a welcome and emotional return in the final moments of Psych 2.

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And therefore, so too does actress Kristy Swanson. Though Marlowe doesn't have much screentime in the film, Swanson perfectly captures the myriad emotions running through Lassiter's terrified but loving wife, and the chemistry between Swanson and Omundson is just as natural and warm as ever before.

Kadeem Hardison as Wilkerson

Kadeem Hardison in Psych 2 Lassie Come Home

Still best known for his turn as the iconic Dwayne Wayne in the 1990s sitcom A Different World, Kadeem Hardison has a brief but pivotal appearance in Psych 2: Lassie Come Home. As Wilkerson, a supposedly comatose patient at the rehabilitation center, Hardison spends much of the film pretending to be unconscious.

He gamely keeps himself that way when Gus launches into a truly bizarre, over the top tickle attack on Wilkerson's feet, and later holds his comedic own when Gus wrestles him to the floor. It's Wilkerson who provides a key piece of evidence to Shawn and Gus when they finally catch him conscious, and Hardison is perfect in his delivery of the news.

Richard Schiff as Dr. Hirsch

Richard Schiff in Psych 2 Lassie Come Home

Psych has always been known for its love of nostalgia and reunions, so it's no wonder that Psych 2 includes yet another example of this with Dule Hill's former The West Wing co-star Richard Schiff appearing. As Dr. Hirsch, the benevolent doctor taking care of Lassiter without charge, Schiff is subdued and serious.

Schiff also expertly portrays Dr. Hirsch as perhaps too good to be true, leaving a shadow of doubt in all of his interactions with Shawn and Gus, even though he is ultimately cleared of all wrongdoing.

Jazmyn Simon as Selene

Jazmyn Simon in Psych 2 Lassie Come Home

Gus hasn't had the most luck in the romance department over the course of the original Psych series, so when the first film introduced Hill's real life partner Jazmyn Simon as the slightly crazy Selene, it proved a welcome change of pace.

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That investment only further pays off in Psych 2, as Simon steals each and every scene she's in. Selene is more grounded and more fully realized in this film, but she's still over the top, hilarious, and an absolute comedic asset to the franchise - all thanks to Simon's talent, and effortless chemistry with real life husband Hill.

Joel McHale as Mr. Lassiter

Joel McHale in Psych 2 Lassie Come Home

The show has never revealed all that much about Lassie's childhood, but Psych 2 more than makes up for that fact with the inclusion of Community alum Joel McHale in the role of Mr. Lassiter. Glimpsed in both flashback scenes and hallucinations, McHale's Mr. Lassiter is as warm and loving as he is curmudgeonly in the traditional Lassiter way.

It's easy to see how Carlton Lassiter became the man he is because of this man, and it's a real testament to the casting of Joel McHale, who nimbly reaches every comedic and dramatic note the role requires.

Kurt Fuller as Woody Strode

Woody Strode undercover with a mustache and fedora in Psych 2 Lassie Come Home

A series regular for the later years of Psych, Kurt Fuller is a welcome sight whenever he appears in any part of the franchise. His over the top undercover role as Woody Strode, alias Dr. A.V. Catalon, in this film is certainly no exception to that rule.

Whether communicating with Shawn and Gus over FaceTime, acting under his assumed persona complete with hammy accent and fake mustache, or engaging in clandestine albeit poorly thought out meetings, Fuller's performance as Strode is just as perfect as it ever was. It feels like barely any time has passed at all.

Jimmi Simpson as Mary Lightly

Jimmi Simpson in Psych 2 Lassie Come Home

Somewhere along the way during the original Psych series, Jimmi Simpson's enigmatic but ill-fated Mary Lightly became something of a supernatural icon. After being tragically killed during a murder investigation, Mary Lightly has appeared in the series multiple times from the beyond, and has now appeared in both films as well.

But no appearance has been more bizarre, and more uproariously hilarious, than Simpson's turn as Baby Mary in the new film. Simpson, now well-known for his Emmy-nominated turn in Westworld, is perfectly made for this role, and for the Psych universe at large.

NEXT: Psych: 5 Best (& 5 Worst) Relationships