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Since 1993, Conan O'Brien has been synonymous with late-night TV. The Harvard graduate who would go on to write for "The Simpsons" and "Saturday Night Live" broke out on his own with his unique brand of late-night comedy that spawned legions of fans across three legendary talk shows, a beloved podcast, and a travel show. His 30-year career (an counting) also found him in memorable hosting gigs at the Academy Awards, the Emmy Awards, and the White House Correspondents' Dinner.

But in between his incredibly busy schedule of making people laugh with his wacky and self-deprecating, yet intellectual and authentic comedy, O'Brien found time to do some acting. However, for his guest role on "How I Met Your Mother," rather than being featured in a standout moment, he popped up in the gang's favorite watering hole for a quick blink-and-you-miss-it cameo.

The appearance can be found in season seven's "No Pressure." In this episode, Ted and Robin share a kiss that could jeopardize their current relationship as roommates and close friends. But before they can talk about it, she is called away to an assignment in Russia. Meanwhile, Barney is convinced that he has finally found Marshall and Lily's fabled sex tape. O'Brien can merely be seen in MacLaren's Pub towards the beginning of the episode when Barney runs out of the bar.

According to Vulture, the leader of Team Coco won the cameo in an auction supporting the Ojai Playwrights Conference. Bays shared that there were different options for O'Brien's cameo, but ultimately, they decided that the non-speaking role would be funnier and more realistic since "every now and then you'll see somebody famous at a bar, but nobody really makes a big deal out of it."

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Throughout the run of "How I Met Your Mother," an ongoing mystery is Robin's life in Canada before she moved to New York. At first, things are relatively harmless, like jokes about the accent or the weather and some small details about her family. But as time passes, the group learns that she was actually a Canadian teen pop star named Robin Sparkles. Her first hit song "Let's Go To The Mall" led her to a tour of the biggest malls across the Great White North, while her second, more artistic single "Sandcastles In The Sand" didn't find the same success.

Some years after that (as we learn in the season six episode "Glitter"), Robin Sparkles would soon find success in the children's educational entertainment (or edutainment) space alongside her best friend Jessica Glitter. Together, they were the stars of "Space Teens," a show that saw them solve math-related mysteries given to them by Canadian national treasure Alan Thicke.

Jessica Glitter is played by pop music maven Nicole Scherzinger. The singer/dancer first made waves as part of girl groups Eden's Crush and The Pussycat Dolls. She would go on to serve as a judge on various talent competition shows such as "The Sing-Off," "The X Factor," and "The Masked Singer." And as an actor, she is best known for lending her voice to Moana's mother Sina in Disney's "Moana" and "Moana 2," as well as her award-winning role of Norma Desmond in the West End and Broadway productions of "Sunset Boulevard." But for fans of HIMYM, Scherzinger will always be one half of the beloved "Beaver Song."

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Before he was known for more dramatic roles in projects like "Godzilla" (2014), "All The Way," or "Breaking Bad," Bryan Cranston landed his first major leading role in the dysfunctional family sitcom "Malcolm In The Middle." After his time as Hal came to an end in 2006, the actor made a quick stop in HIMYM's New York City to play Ted Mosby's boss before heading to New Mexico to step into Walter White's jumpsuit.

Cranston first appeared as Hammond Druthers, Ted's obnoxious boss at the architecture firm, in the sixth episode of season two. While he constantly berated Ted and his team, Druthers had a run-in with Lily where she stole his baseball signed three times by Pete Rose to punish him for the mistreatment of his co-workers. This led to Lily getting fired, but Aldrin Justice was served in the end when Hammond's very phallic design for a building was rejected in favor of Ted's more classic skyscraper.

Following these events, Ted was promoted to be the project leader, which meant that he was now Druthers' boss. The demoted architect was still as jerky as ever though, so Mosby was forced to fire his former superior, even after Druthers' went through a rollercoaster of emotions due to his birthday, his divorce, his cherished dog's death, and a heart attack.

Despite leaving things on a sour note between them, Hammond Druthers popped up one more time in the "How I Met Your Mother" universe to offer Ted a job in season nine. However, after finally meeting Tracy McConnell, he would ultimately turn down the job in Chicago with his old colleague and stay in New York.

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Just like Robin Scherbatsky, Barney Stinson's backstory slowly gets uncovered as "How I Met Your Mother" progresses. Initially, his family life, his career, and (if you happen to be one of the ladies that he's attempting to pick up) sometimes even his real name remains a mystery. But in the second season, we finally start to meet other members of the Stinson family, including Barney's Black, gay brother James (played by Wayne Brady) and their mother Loretta.

The first time we see the matriarch of the Stinson clan is in season four, where she is played by Frances Conroy. However, Loretta Stinson is first introduced on the show in season two in flashbacks... only shown from the waist up. But if you're a fan of "Will & Grace," "Bob's Burgers," or "Parks and Recreation," then you will definitely recognize the voice of Barney's mother.

While you don't see her face, HIMYM fans can definitely hear Megan Mullally lend her voice to Loretta. She can be heard in the episode "Single Stamina," telling the younger versions of Barney and James that, when she was pregnant with them, she only ate very specific flavors of ice cream (vanilla and chocolate) before telling the older versions of the kids that they were being racist for continuing to ask why they look different. Later in the season, we also find out that she told Barney that his father was legendary "The Price Is Right" host Bob Barker. But after the second season, Conroy takes over the character from season four onwards.

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"Ted Mosby: Sex Architect" is probably one of the funniest bits from the entirety of "How I Met Your Mother." At the very least, it's one of my favorites. Either way, this comes about in the season three episode "I'm Not That Guy," when Barney finds a pornographic film starring an actor named Ted Mosby. Feeling uncomfortable about the existence of a popular porn star with his name out in the world just as he's beginning to gain recognition as an actual architect, the "real" Ted goes with his friend to a convention to meet the adult film performer that some people are starting to mistake for him. When the Teds come face to face, sex worker Ted is played by Kevin Heffernan.

While that name may not sound immediately familiar, viewers familiar with the comedy troupe Broken Lizard will recognize him immediately as Farva from "Super Troopers" and "Super Troopers 2" or Landfill (and Gil) from "Beerfest." He also created and stars in the incredibly underrated TruTV sitcom "Tacoma FD" alongside fellow Broken Lizard member Steve Lemme.

But what becomes of Ted Mosby: Sex Architect? Well, first, his real name is Steve Beil. Second, he chose his name to honor Ted for standing up for him when he was being picked on by bullies at a young age. And finally, when the regular architect Ted tries to convince his porn counterpart to change his stage name to Lance Hardwood, Steve takes the suggestion and runs with it. Sort of. His next film is titled "Lance Hardwood: Sex Architect, Starring Ted Mosby." And with the help of Barney, the film is shot on location Ted and Marshall's apartment.

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No one wants to relive their worst moment in life over and over again. Unfortunately for Ted, that's exactly what happened when "The Wedding Bride" hit theaters. The popular romantic comedy retold the events leading up to the moment that Stella Zinman (played by "Scrubs" alum Sarah Chalke) left him at the altar. Although, the details were a bit skewed, thanks to screenwriter (and Stella's husband/father to their daughter) Tony. So just like the rest of the world at that time, Ted watched as rom-com veteran Malin Akerman starred in his worst nightmare.

Yes, when the "How I Met Your Mother" writers decided to create a fake "chick flick" for the show's fifth season, they tapped a bona fide star of the genre to play the fictional Stella. In addition to her acclaimed roles in "Watchmen," "Rock of Ages," and "The Final Girls," Akerman's resume also includes some fan favorite rom-coms such as "27 Dresses," "The Heartbreak Kid," and "The Proposal." Interestingly, she also played opposite HIMYM star Josh Radnor in "Happythankyoumoreplease," which he also wrote and directed.

This reunion between Akerman and Radnor wasn't as complementary for the male lead though. Instead, fictional Ted, AKA "the most corrupt architect in New York City" Jed Mosley, was played by former "Saturday Night Live" cast member Chris Kattan. With the whole episode being about the types of baggage that people carry around while dating in their 30s, the real Ted has to put up with the masses talking about his pain while using Jed's trademark over-the-top catchphrase, "No can do-sville, babydoll!"

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While Ted and Barney are preoccupied with Ted Mosby: Sex Architect, Marshall has a big decision to make in "I'm Not That Guy." After passing the bar, he manages to land his dream job as part of the legal department at the Natural Resources Defense Council, which fights the good fight to save the environment. However, he also receives an offer from Nicholson, Hewitt, and West, the law firm representing reprehensible clients who are polar opposites of the NRDC. Naturally, "Big Fudge" intends to turn the job down. But thanks to charming interviewer Jefferson Coatsworth, who is played by the incomparable John Cho, he has a harder time doing that than originally anticipated.

Cho has a deep history with the cast of "How I Met Your Mother." Before appearing in acclaimed projects like "The Afterparty," "Searching," and J.J. Abrams' "Star Trek" franchise, his big breakout role was MILF Guy in "American Pie" alongside Alyson Hannigan. Then, when Cho made history with Kal Penn in "Harold and Kumar Go To White Castle," Neil Patrick Harris went from a cameo in that first film to basically a full-fledged lead in the rest of the franchise. And when Cho starred in the short-lived WB sitcom "Off Centre," Josh Radnor was originally meant to play a lead in that show before another "American Pie" alumni Eddie Kay Thomas stepped into the role.

In the show, Coatsworth made Marshall an offer that he could not refuse, especially with Lily's mounting credit card debt. However, as Future Ted would tease in his narration, Cho's character wouldn't be around for very long at the firm because he ended up in jail over some shady business. 

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While the show isn't really considered a musical like "Glee" or "Smash," music is deeply embedded in "How I Met Your Mother." With original bangers like "Nothing Suits Me Like A Suit," "Let's Go To The Mall," and "You Just Got Slapped," the series has given birth to so many earworms that have earned premium spots on our pop culture playlists. Even a song as goofy as "Bang Bang Bangity Bang" lives in our heads rent-free. However, you might recall that the season five episode that birthed that song also features pop music icon and acclaimed actor Jennifer Lopez.

Back in 2010, Lopez appeared as Anita, the author behind the self-help book "Of Course You're Still Single, Take a Look at Yourself, You Dumb Slut." Thanks to Robin, the writer has targeted notorious womanizer Barney in order to teach him a lesson. But after he reads Ted's copy of the book, the suited up savant tries to find a loophole in the writing that will cause Anita to break her own rule and sleep with Barney before going on 17 dates.

While this storyline also involved the memorable song "Super Date," the main takeaway from this episode is that Robin was feeling upset over the way Barney had seemingly moved on from their relationship so quickly. Ultimately, he proves to be a good friend, but only after using the power of no against Anita and refusing to sleep with her.

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As shown by this list, "How I Met Your Mother" has had an impressive collection of guest stars throughout its run. Beyond the big names listed here, Britney Spears, Enrique Iglesias, Katy Perry, Kal Penn, and Katie Holmes are just a few more standouts. But out of all the guests to appear on the show, very few have the acting pedigree of Michael York.

Even before graduating from Oxford in 1964, York built up an impressive resume in the theatre under the likes of Laurence Olivier and Franco Zeffirelli. His collaboration with the latter led to his first foray into film as Lucentio in "The Taming of the Shrew" in 1967 and Tybalt in "Romeo and Juliet" in 1968. From there, he went on to star in classic films "Cabaret," "Logan's Run" (which he almost passed on), and "The Island of Dr. Moreau" while maintaining a presence onstage. Later in his career, he became well-known for portraying Basil Exposition in the "Austin Powers" franchise.

But even with a killer filmography like his, York frequently worked in television as well. On top of the prestige miniseries and TV movies, he also appeared on "Batman: The Animated Series," "Babylon 5," "Curb Your Enthusiasm," and "The Simpsons." For the fifth HIMYM season, he played Jefferson Van Smoot, a distinguished guest at a high society party where Ted feels right at home. In fact, he almost misses "Robots Versus Wrestlers." Although, with the emergence of his doppelgänger (a professional wrestler), he is compelled to join his friends immediately.

While York's role as Van Smoot is brief, he does have a fun scene with Jason Segel's Marshall.

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Before he took the world by storm through the catchy songs of "Hamilton," "Moana," and "Encanto," renaissance man Lin-Manuel Miranda was making waves on Broadway with "In The Heights" and his hip-hop improv group Freestyle Love Supreme. Because of those two projects, that made him the perfect person to call on when "How I Met Your Mother" decided to deliver an all-rhyming episode centered around Marshall telling Baby Marvin some bedtime stories on the way to Farhampton for Barney and Robin's Wedding.

In HIMYM's 11th episode of the ninth season, Miranda plays a fellow bus passenger named Gus. He and the other passengers agree to speak in rhymes as they soothe Marvin and help him stay asleep rather than make a fuss and disrupt everyone's journey. In between Marshall's three stories, viewers check back in on the bus to see how the young Ericksen is doing. But at one point, the delirious father is out of rhymes. Luckily, Gus steps in with an insane flow about trying to find a rhyme for Canada.

While our time with Gus was short-lived, it did leave a lasting impression. After their bus broke down, Marshall learns that the wedding venue is only a few miles away. Despite coming to regret that decision, that's when he decides to walk the remaining way. Plus, we get a reprise of the song "Marshall Versus The Machines," which originally motivated Marshall during the season six race between the gang to get a glimpse of Woody Allen at a restaurant.