It's been almost ten years since fans bid farewell to The Office. Without this fantastic show, audiences' lives would be devoid of "that's what she said" punchlines and missed out on prank ideas from the Dunder Mifflin's Scranton gang. One of the pioneers of mockumentary TV, the sitcom has earned a special spot in fans' hearts with its dry, sarcastic humor intertwined with heart-warming moments.

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The Office is one of those great shows that require multiple viewings. Not only because of how hysterical and comforting it is but also the random moments when celebrities decided to make an appearance on the series.

When Conan O'Brien Is In New York

Conan O'Brien in The Office

Conan O'Brien's cameo appearance occurs when Michael Scott (Steve Carell) visits the Rockefeller Center in New York. In Season 2, Episode 16 ("Valentine's Day"), the American talk show personality stuns audiences when he walks past the crew's camera without a slight interest in his surroundings.

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Michael misses his chance to meet a celebrity like O'Brien as he confuses a random woman with American comedian Tina Fey. When the camera crew tells Michael about O'Brien, the disappointment on his face says it all as he whines about the "fake Tina Fey." O'Brien would later drop by the Scranton branch when he hosts the 2006 Emmy Awards and not-so-subtly develops a crush on Pam Beesley(Jenna Fischer).

When Jim Carrey Wanted To Be The Regional Manager

Jim Carrey in The Office
Image via NBC

One of the most memorable guest stars in the long-running sitcom belongs to none other than Jim Carrey. A few public figures have flexed their comedic side during Dunder Mifflin-Sabre's search for the new Regional Manager in Scranton. Carrey still manages to steal the spotlight when he shows up unexpectedly in Season 7, Episode 27 ("Search Committee — Part 3").

The renowned actor, known for his essential performances in The Mask and The Truman Show, does not resort to his usual Jekyll-Hyde, physical comedic style in this cameo. Just known as the "Finger Lakes Guy," Carrey successfully imprints in viewers' minds with his quirky talking style and begs the question — is he the "Scranton Strangler?

When Warren Buffett Becomes A Cheapskate

Warren Buffett in The Office

Aside from Carrey, another famous personality that no one expected to see in The Office would be billionaire business mogul — Warren Buffett. With his enormous amount of wealth and influence, the Buffett the world is familiar with could have easily saved Dunder Mifflin-Sabre's perilous circumstances.

In Season 7, Episode 25 ("Search Committee - Part 1), he dons a vastly different yet hilarious persona of a penny-pincher during his interview with Jim (John Krasinski), Dwight (Rainn Wilson), and Gabe (Zach Woods). The ludicrous contradiction between Buffett's affluence off-screen and his cheese-paring persona on-screen makes for some striking imagery.

When Evan Peters Is Michael's Nephew

Evan Peters in The Office

Before amazing audiences with his role as Quicksilver in the X-Men franchise, Evan Peters dons the character of Luke Cooper, Michael's insolent, bratty nephew/assistant in the paper company. In Season 7, Episode 1 ("Nepotism"), Cooper increasingly gets on the Scranton team's nerves with his childish antics, such as causing Phyllis (Phyllis Smith) to lose a client, distracting everyone by pointing a laser at inappropriate behaviors, to name a few.

Cooper's incorrigible behavior eventually leads to Michael's outburst, where he repeatedly spanks Cooper in front of the whole office. Cooper ends the episode by storming out of Dunder-Mifflin while waving rude hand gestures. According to Creed (Creed Bratton), the brat even trash-talks everyone in the office on Twitter.

When Ken Jeong is Michael's Improv Partner

Ken Jeong in The Office

Before the release of "Threat Level Midnight" much later in the series, Michael is seen attending an improvisational class in Season 2, Episode 9 ("Email Surveillance"). Usually known as a drama-magnet and crowd-pleaser, Michael surprisingly struggles throughout the class as he bears an obstinate fixation on his sole persona — a gun-wielding action hero.

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The Scranton branch manager terrorizes his classmates, including The Hangover star Ken Jeong, with insensible improvisational scenarios. As Jeong demonstrates significantly better ad-lib skills, Michael gives up on preserving the team spirit and continues his erratic behavior. You can't blame Jeong for breaking the bad news to Michael about how he is not invited to the team's after-improv dinner gathering. Luckily, audiences still see Michael with his gunfighter persona in his directorial masterpiece.

When Jack Black, Cloris Leachman, and Jessica Alba Are In A Fictional Movie

Jack Black & Jessica Alba in The Office

Probably one of the most arbitrary guest appearances in TV history, Jack Black and Jessica Alba play a couple in a fictional movie bootlegged by Andy (Ed Helms), titled Mrs. Albert Hannaday. Clearly not a real movie that exists outside the context of The Office, the film features a bizarre love triangle where Black's character falls in love with Alba's mother (played by Cloris Leachman to boot) in a plot-filled with lies and betrayals.

This fictional movie serves no major plot-moving purposes, instead of providing some comedic relief and insight into Pam's parents' fragile marriage in Season 5, Episodes 14 and 15.

When Dakota Johnson is Kevin's Replacement

Dakota Johnson in The Office

Before meeting Christian Grey in Fifty Shades of Grey, Dakota Johnson plays another office newbie role, one with the same first name as hers in the series finale. After Dwight fired Kevin (Brian Baumgartner) for his "kelevens," Dakota is hired as Kevin's replacement and completes the new, fresh-faced generation of the paper company.

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Not much is known about her personality and life outside the office, yet her youthful energy is perfectly juxtaposed with Kevin's slothful temperament. However, the season finale hints at a new office romance like Jim and Pam as the chemistry between Dakota and colleague Clark (Clark Duke) is evident.

When Joan Cusack Is Erin's Real Mother

Joan Cusack in The Office

As Pam's stand-in for the new secretary of Dunder Mifflin Scranton, Erin (Ellie Kemper) quickly won fans' hearts with her optimism and bubbly personality. Her upbringing in the orphanage is often referenced throughout the series and piques viewers' curiosity as to who Erin's parents are.

The answer is finally revealed as her mother appears in the series finale, played by Oscar-nominated actress Joan Cusack. During the Q&A session for their documentary, her mother asks if Erin would hate her absent mother, to which Erin denies in a roundabout manner of speech. As she repeatedly calls out "Erin," Erin eventually gets the hint and hugs her mother. The mother-daughter reunion encapsulates one of The Office's most touching scenes.

When Randall Park is Asian Jim

Randall Park in The Office

In one of The Office's best cold opens, Jim pulls yet another prank on Dwight when he gets Netflix film Always Be My Maybe star Randall Park on board to be his "actor friend," Steve. In Season 9, Episode 3 ("Andy's Ancestry"), Steve stands in for Jim when the prankster is in a dentist appointment, tricking Dwight into thinking that Jim has had for the whole eight seasons been Asian.

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From Steve knowing Jim's voicemail password to Jim and Pam's family photo changed into a bi-racial household. Dwight loses his mind and starts questioning reality. Hats off to Dwight for not seeing race.

When Steve Carell Returns As Michael Scott

Steve Carell in The Office as Michael Scott Before & After

As the life and soul of the series, fans would be devastated if Steve Carell fails to make another appearance before the show ends. Having him return as Michael Scott in Dwight and Angela's (Angela Kinsey) wedding is the perfect way of welcoming Carell back for The Office family reunion.

Before Dwight's wedding with Angela, Jim pulls his best prank ever when he announces his decision to step down from being Dwight's best man, much to the latter's horror. Dwight's panic subsides before escalating into sheer happiness when it is revealed that Jim has asked Michael to take over as Dwight's best man. After two seasons of absence, delighted fans are again treated with Michael's signature that's-what-she-said joke in this poignant final episode.

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