Hollywood is a small town, but it's not like all the stars are best friends! That's what makes it fun when celebrities meet their favorite stars on red carpets, backstage at concerts, and even while catching flights at airports. With the rise of the selfie , more and more stars are capturing their run-ins and sharing the special moments with us on social media. Keep reading to see the most surprising selfies we've seen so far, and then fill your feeds with follow-worthy celebrities .
Source: Facebook user Joseph Gordon-Levitt , Getty / Pool , Instagram user katyperry , Twitter user zachbraff 
Jennifer Lopez and First Lady Michelle Obama huddled  for their smiley selfie. The two linked up at the Unity Luncheon in NYC in July.
The power of the 2014 Emmys brought Minnie Driver , Jesse Tyler Ferguson, and Matt LeBlanc together, and they honored it with this selfie.
Sofia Vergara let all of her followers know she shared a moment with Lady Gaga .
Chris Hardwick had "REALLY GOOD SEATS" at the 2014 Emmys, making this this selfie with Bryan Cranston and Aaron Paul possible.
Emma Roberts and Liam Payne hit us with their picture-perfect looks in this adorable picture, which she took on the red carpet at the 2013 American Music Awards.
Chris Hardwick is often in the right place for a star-studded selfie, like the time he was all-too-thrilled to nab one with Ben Affleck , Henry Cavill, and Gal Gadot at the Batman v Superman: Dawn of Justice panel at Comic-Con in 2014.
As the most retweeted picture ever , Ellen DeGeneres 's Oscars selfie doesn't need to be explained.
Nicki Minaj pouted it up when she got Jennifer Lopez  to lean in for a picture at the 2014 MTV VMAs.
There's too much hotness in this snap of Jon Hamm  and Zach Braff , and Zach knows it. "Here's one for the ladies," he wrote in the caption.
When Gwyneth Paltrow  saw Demi Lovato on her flight, she just had to take a selfie.
The only thing more surprising than Jessica Biel  and Anne Hathaway  sharing a selfie at the Oscars: their wild expression!
Ellen DeGeneres famously dissed Liza Minnelli  at the 2014 Oscars, but it didn't stop the two from taking a picture together. "#Besties," Ellen tweeted.
Here's what happened when Lady Gaga  and Bill Murray  visited Late Show With David Letterman in April 2014.
Comedy mainstay Julia Louis-Dreyfus  smiled wide with newcomer Lupita Nyong'o at the 2014 Golden Globes.
Inspired by Ellen DeGeneres 's Oscars selfie, Jimmy Kimmel got the Clintons to show off their pearly whites during a Clinton Global Initiative University event.
Gwyneth Paltrow 's "#girlsnight" snap with Nicole Richie , Chelsea Handler, Naomi Watts , Gwen Stefani , and Stella McCartney  proved the ladies are actually real-life pals.
Rebel Wilson held her camera steady to score a picture with Anne Hathaway  at the 2013 Critics' Choice Awards.
This kid nabbed a selfie with Paul McCartney and Warren Buffett when the unlikely pair grabbed dinner in Omaha, NE, in July 2014.
If it weren't for the Oscars, would Joseph Gordon-Levitt and Emma Watson  have ever had the chance to take an animated picture like this?
Adele "graced" Katy Perry  with her presence at the "Dark Horse" singer's London concert in June 2014.
Katy Perry  brought her "pink pony to the White House to holler" at Vice President Joe Biden in June 2014.
Meryl Steep, the queen of Hollywood, and Hillary Clinton, the most powerful woman in Washington, united for a smiley selfie at the Kennedy Center Honors in December 2012. Meryl donated her image to a charity. For $200, you can have a copy of the iconic selfie  and contribute to Shutter to Think's education efforts.
Demi Lovato looked starstruck when she posed for a snap with former President Bill Clinton at the Unite4:Humanity Gala in February 2014. "Too excited to filter this... NO BIG DEAL - #Selfieswiththeprez.... Bill Clinton - so nice to meet you!!!!" she wrote in the caption.
For TV fans, it felt like two universes were colliding when Orange Is the New Black stars Uzo Aduba and Taylor Schilling hung out with Modern Family's Jesse Tyler Ferguson and his husband, Justin Mikita, during the White House Correspondents' Dinner weekend in May 2014.
Diddy  hung out with Mona Lisa. (OK, maybe it only looks like she's aware he's taking a selfie).