Bidding farewell to a favorite show is never fun. But after gifting the world with an inside scoop of their private lives for 15 years, the Kardashian-Jenner clan was ready to call it quits. Fans of Keeping Up with the Kardashians can still revel in the memories of the Kardashian-Jenners' lavish parties, endless drama, and tantalizing looks into the glitz and glam of the American "royal" family.

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A big part of living the lux life is being surrounded by equally rich, fabulous, and famous friends and acquaintances. Over the course of its 20 season run, Keeping Up with the Kardashians has featured an endless parade of guest stars connected to the family in one way or another. From former romantic flings (who just so happen to be celebrities) to social media stars, audiences will surely miss the excitement brought about not only by the Kardashians but the other surprise celebs as well.

Adrienne Bailon

Three images side by side of Adrienne Bailon and Robert Kardashian next to each other on KUWTK

Robert Kardashian Jr. might be a bit of an unknown presence for younger fans of the show since the reality star severely cut down his screentime in later seasons. But early on, Rob was featured on several episodes and storylines as a series regular. More often than not, he brought his girlfriends along for the ride.

One of those girlfriends was none other than Disney star and former Cheetah Girl, Adrienne Bailon. The singer and actress made quite an impact due to her already existing fanbase and her antics with Khloé Kardashian. Unfortunately, Adrienne, who went on to star on The Masked Singer, and Rob broke up in 2009.

JoJo Siwa

Kim Kardashian, North West, and JoJo Siwa making the peace sign in Keeping Up With The Kardashians

Once upon a time, the Kardashian-Jenner sisters were the main stars of the show. And though that remains true, for the most part, dynamics began to shift once their babies came into the picture. Kim Kardashian's children, in particular, were heavily featured on KUWTK, even providing the audiences with their own storylines.

Kim and Kanye West's elder daughter, North, got to meet one of her idols on season 17 of the show. JoJo Siwa, of Dance Moms fame, was a welcomed surprise in the series, and fans can hardly forget Kim's shocked expression as she FaceTimed husband Kanye West to show him the vast amounts of merchandise JoJo had to her name.

Hugh Hefner

Hugh Hefner and one of his girlfriends posing together in matching robes and captain hats

Back in Season 1, when the vast empire of the Kardashians was just beginning, the show included a storyline surrounding Kim's decision to be featured on the cover of Playboy magazine.

To the excitement of many, none other than the late Hugh Hefner, founder of the magazine, made a cameo, alongside his then-girlfriends. This celebrity appearance might have taken place over a decade ago, but it will hardly be relegated to the back of fans' minds — in large part because it happened during the episode that spurred the meme "You're doing amazing, sweetie!"

Sia

Kim Kardashian and Sia talk and laugh with her two children in Keeping Up With The Kardashians

The Kardashians are often surrounded by extremely talented people, and one such person happens to be Sia. Over the years, the "Chandelier" singer has become close friends with the family, often performing at or attending their events.

Related: 10 Best Keeping Up With The Kardashians Couples, Ranked

Over the course of two dozen seasons, Sia has been featured in five episodes of the show, a cameo that audiences thoroughly appreciated, as she is a notable departure from other celebrities who appeared on Keeping Up with the Kardashians.

Alex Rodriguez

Kendall, Khloe, ARod, Kris, and Kim posing with softball bats in Keeping Up With The Kardashians

The famous family loves to come up with fresh new ways to bond and have fun. These events range from run-of-the-mill parties to over-the-top pranks. And in 2018, they got even more creative.

Having decided to partake in a softball game for charity, the Kardashians recruited Alex Rodriguez, a professional baseball player and former romantic partner of singer Jennifer Lopez. Watching the family have so much fun together as they learned from Rodriguez was quite a treat, and small injuries aside, it remains one of the most light-hearted cameos to date.

Vera Wang

Two pictures of Vera wang smiling, standing in her studio in Keeping Up Wit The Kardashians

As some of the most popular influencers in the world, the Kardashian-Jenners hold a lot of power. Style is a fundamental part of their identity and as trendsetters of the highest order, they have some of the best connections in the world of fashion.

Bringing one of those connections into the show was a natural progression. But when it turned out to be Vera Wang, the legendary wedding dress designer, fans all across the world gasped in astonishment. Wang made not just one, but two appearances on the show: once, when Khloe wed Lamar Odom, and another, when Kim married now ex-husband Kris Humphries. If there was any doubt still lingering about the Kardashians' taste and powerful connections, this cameo ought to have mitigated them.

Gigi Hadid

Kendall and Gigi having drinks in Keeping Up With The Kardashians; backstage at the VS Show

The evolution of Kendall Jenner from an awkward teenager to one of the highest-paid models in the world (according to Harper's Bazaar) was one of the most compelling arcs on the show. With her entrance into the high-fashion world, came a series of friendships with likewise famous, beautiful, and successful models.

Gigi Hadid, who'd also been featured on The Real Housewives of Beverly Hills, showed up in a couple of KUWTK episodes, much to the delight of her fanbase, which has a lot of crossover with Kendall's and Kylie's. It was a lot of star power in one room!

Addison Rae

Kim Kardashian and Addison Rae sitting side by side ​in Keeping Up With The Kardashian

The world at large was surprised at the budding friendship between 20-year-old TikTok star Addison Rae, recently cast in the She's All That remake, and 42-year-old Kourtney Kardashian, including the latter's family.

Related: 10 Of The Best-Ranking Episodes of Keeping Up With The Kardashians, According To IMDb

Addison made her debut on the show, and it was a memorable one for several reasons. From teaching Kim the "WAP" dance to being interrogated by the entire family about her intentions towards Kourtney, Addison's cameo was the gift that kept on giving.

Ariana Grande

Kris Jenner and Ariana Grande wear matching pink tracksuits in Keeping Up With The Kardashians

One of the most streamed artists of her generation on Spotify, Ariana Grande has proved time and time again what a talented singer she is. Her ability to take heartbreak and spin into gold was never more apparent than when the song "Thank U, Next" was released.

A music video soon followed, inspired by iconic movies like Mean Girls and 13 Going On 30. And who better than Kris Jenner to play the part of supportive mom? Kris' time on the set was a joy to behold, and Ariana's immense presence added a little extra something to the episode.

Paris Hilton

Kim Kardashian and Paris Hilton staring at their flip phones in Keeping Up With The Kardashians

The connection between Kim Kardashian and Paris Hilton will never be lived down. There was a time when Kim was simply part of Paris' entourage, but things took a very different turn, and she's now on top of an empire worth $1 billion, according to Harper's Bazaar.

Thankfully, fans got to experience this iconic dynamic before the Kardashians closed their doors to the world. Paris Hilton made a cameo on the show, helping her old friend Kim with a SKIMS photoshoot. Seeing these two reunite on screen after so much took place in both their lives was nothing short of legendary.

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