13 Celebs Who Got to Cameo on Their Favorite Shows

From Britney Spears to Josh Groban, these celebs were invited to be a part of their favorite program -- and a few even got asked to come back more than once!

Find out which celebs guest starred on their favorite shows…

1. Prince

Prince was such a big fan of "New Girl" that he actually had his manager send an email directly to Zooey Deschanel asking if he could appear on the show. At first, she says she thought the whole thing was a prank -- until she had some people look into it.

"I had several people check it out. It turned out it was his manager. You know, you never know. When you put stuff out there, you're in the entertainment business, you never know who might just be flipping channels and find your show. And randomly, Prince found the show, and he was watching it every week with his band, and they'd watch it on tour, and it was like he couldn't miss it, and they were really invested in the Nick and Jess relationship. It was just one of those really surreal moments," Zooey said on "Jimmy Kimmel Live."

Episode: Season 3 "Prince"

2. Britney Spears

Back in 2008, Britney Spears made an appearance on "How I Met Your Mother" after telling co-creators Carter Bays and Craig Thomas that she loved the show. Britney was invited to play Abby, a ditzy receptionist at the dermatology office where Ted was getting a tattoo removed. While she fell hard for him, Ted fell for his doctor -- and Barney stepped in to console Abby. Britney was so well received, she was invited back for another episode later in the season.

"We got a call a few weeks after the writers strike ended saying that Britney Spears wanted to be on our show. And she specifically wanted to be in the episode 'Ten Sessions,' which sent a chill down our spines, because that’s the one where we meet Stella. I immediately imagined Britney playing Stella and had a minor panic attack, because it's such a big role and needed a proven, experienced actress like Sarah Chalke. But to her credit, Britney liked the character of Abby, and wanted to play that part. So we said sure! And by golly she put our show on the map. It can't be overstated. Britney Spears rescued us from ever being on the bubble again. Thanks Britney!" Carter wrote on Reddit.

Episode: Season 3 "Ten Sessions,"  "Everything Must Go"

3. Mark Hamill

Mark Hamill got the chance to guest star on his favorite show "What We Do In The Shadows" because he tweeted about it so much! The actor explained that many of the shows he loves get canceled so he wanted to make sure others knew about it. His social media activity put him on the show's radar and they ended up inviting him to play Jim the Vampire, a nemesis of Laszlo Cravensworth.

"I always get nervous about shows I like, because I find something I really love and it gets canceled. So I tweeted about it several times, trying to get my followers to give it a try. Apparently that's what put me on their radar, and the next thing I know they asked me to come on the show. I thought I'd be playing a meter reader, or a next door neighbor, or someone at the Department of Motor Vehicles. When I found out that they wanted to play what was called in the script The Vampire, I just flipped out, I couldn't wait," Mark told Vulture.

Episode: Season 2 "On the Run"

4. Kesha

Kesha landed a guest role on "Jane The Virgin" but she almost didn't go to the audition! The musician explained that she was called and asked to read for the cameo but it was her first day off in a while and she was looking forward to relaxing. She says that when she found out which show it was for, everything changed. Kesha ended up playing Jane's noisy rock n roll neighbor.

"I was really excited! They called me randomly. I was finally supposed to have a day off because I hadn't had one in three weeks, and they called me and they were like, 'Can you do this audition?' And I was like, 'Ugh, today's my day off.' And they said, 'Oh, it's for Jane the Virgin.' And I said, 'Oh yeah, f--- yeah,'" Kesha told People.

Episode: Season 2 "Chapter Twenty-Four"

5. Lin-Manuel Miranda

Lin-Manuel Miranda has been a longtime fan of "Brooklyn Nine-Nine" and even campaigned for the show to be renewed when it was canceled, so it only made sense for him to make a guest appearance on the show. It all came together when Lin-Manuel made his cameo as Amy Santiago's perfect older brother, David, during season six.

Episode: Season 6 "The Golden Child"

6. Josh Groban

Josh Groban was a massive fan of both the British and American versions of "The Office" before he was asked to be on the show. When he got the call to audition to play Andy's younger brother Walter Jr., he immediately said yes.

"I have been a huge fan ever since it was an English show. I loved the DVDs of the British version. When it came to America, like everyone, I loved it and thought what a brilliant job they did bringing it overseas and giving it its own unique, hilarious identity. I've watched every season, so when I got the call to be involved I was thrilled," Josh told DigitalSpy.

Episode: Season 8 "Garden Party," Season 9 "The Boat”

7. Jesse Eisenberg

Jesse Eisenberg was such a big fan of "Modern Family" when it was airing that he actively had his agent check in to see if there were any open roles. Finally, the perfect part popped up for him where he played Mitch and Cam's over-the-top environmentalist neighbor.

"Jesse Eisenberg had been very proactive about saying he'd like to do the show when he ran into people and having his agent check in. And we finally found the perfect role for him as Mitch and Cam's neighbor, and he was wonderful," casting director Jeff Greenberg told Variety.

Episode: Season 5 "Under Pressure"

8. Ed Sheeran

Ed Sheeran was an avid viewer of "Game of Thrones" so when he was asked to make a guest appearance on the show as a surprise for Maisie Williams, he had to agree. During the premiere of season seven, he played a Lannister soldier who sat around a campfire with Maisie's character Arya Stark.

"She's always been awesome. I don't think they had written the ending yet. It was meant to be her last season, but it wasn’t. And as a surprise for her, [they got] me on. So, she was meant to turn up on set and I was by the fire," Ed said on the "Armchair Expert" podcast.

Episode: Season 7 "Dragonstone"

9. Michelle Obama

Michelle Obama's daughters Sasha and Malia were big fans of "iCarly" growing up so when she was asked to guest star on the show, she had to say yes. She used the opportunity to promote her initiative to support military families, as Carly's father was an Air Force colonel in the show.

Episode: Season 5 "iMeet the First Lady"

10. Jason Alexander

Jason Alexander has been a fan of "Star Trek" since he was a kid and says that William Shatner actually inspired him to begin acting. He had been asked to make an appearance in the franchise on several occasions but it never worked with his schedule. Finally, he was able to join the cast during season five of "Star Trek: Voyager."

"I had put the word out that I wanted to be part of the Trek world. Each of the series would come to me and either the dates were not good for me or, more often than not, they wanted me to play a human -- and kind of a "George"-like human. I told them the big departure for me would be to play an alien. I did so much histrionics as George, I was kind of hoping I'd wind up as a Vulcan so that I'd get to play some great intellect. It was finally 'Voyager' that understood that and called with the perfect part," Jason said.

Episode: Season 5 "Think Tank"

11. Shaquille O'Neal

Shaquille O'Neal, AKA Shaq, was such a big fan of "Southland" that he decided to reach out to the team to request a guest spot on the show. And the role only made sense as Shaq has served as a reserve officer with both the Port of Los Angeles police and the Miami Beach police department.

"Southland is one of my favorite shows, so one day I just got the number and I called them and I was like, 'This is Detective O'Neal, and I would like to play a police officer [on your show].' They were like, 'This is not Shaq!' I said, 'This is really me.' I e-mailed them a picture [of me in my police uniform] and I told them I would like to be on the show and I’m shooting next week. I'm a police officer in real life and that show really depicts how they do it in life," Shaq told Access Hollywood.

Episode: Season 5 "The Felix Paradox"

12. Jason Mantzoukas

Jason Mantzoukas has been a longtime fan of "Gilmore Girls" and actually appeared on the "Gilmore Guys" fan podcast five times. He was never able to be on the original show but when the series got a revival on Netflix, he was invited to play Naomi Shropshire's lawyer in the second episode.

Episode: "Spring"

13. Patrick J. Adams

Patrick J. Adams has Twitter to thank for his guest starring role on "Orphan Black." After tweeting that he wanted to be on the show, his wish was granted when he was asked to play Jesse, a "brave but regular guy" who finds himself in the middle of clone drama.

Episode: Season 2 "To Hound Nature in Her Wanderings," Season 3 "History Yet To Be Written"