Today is National Best Friend Day, and we're celebrating by rounding up pictures of our favorite celebrity buddies. Take a look at girlfriends Beyoncé and Gwyneth Paltrow , supportive pals Robert Pattinson  and Katy Perry , and beautiful buds Penélope Cruz  and Salma Hayek . There's also Leonardo DiCaprio and his longtime best friend Tobey Maguire , plus so many more. Read through to see them all!
Busy Philipps and Michelle Williams
Busy and Michelle became buds on the set of Dawson's Creek in the '90s. Busy even set up Michelle with her former boyfriend, Jason Segel .
Katy Perry and Robert Pattinson
Katy is close friends with Rob, and since she reportedly provided him with a shoulder to lean on when he broke up with Kristen Stewart , the duo have spent time together in LA and partying at Coachella .
Zach Galifianakis and Bradley Cooper
Zach and Bradley were buddies long before they starred together in The Hangover. Bradley even made an appearance on Zach's short-lived VH1 talk show, Late World, back in 2002 and was one of the first stars to appear on his Funny or Die Between Two Ferns series.
Minka Kelly and Mandy Moore
This duo has been besties since at least 2007  and we can't help but notice that they could also practically be sisters!
Ryan Reynolds and Sandra Bullock
Ryan and Sandra were introduced by a mutual friend years ago and formed a strong friendship on the set of 2009's The Proposal. They supported each other through divorces, his from Scarlett Johansson  and hers from Jesse James. Ryan's even close with Sandra's little one, Louis.
Charlize Theron and Kristen Stewart
Charlize and Kristen got to know each other while filming Snow White and the Huntsman in 2013 and became fast friends. Charlize told Access Hollywood of Kristen, "I really, I really, really love that girl. I love that girl, like, I would jump off a building for that girl. She's amazing, she's amazing."
Kelly Osbourne and Miley Cyrus
Being the daughters of famous musicians may explain the bond between Kelly and Miley. The two have been friends ever since they got close on the set of the straight-to-DVD film So Undercover.
Taylor Swift and Emma Stone
Taylor and Emma met at the Young Hollywood Awards six years ago, and their friendship blossomed from there. Taylor told us in 2011 that Emma is "like a sister to me. She can predict my thoughts."
Drew Barrymore and Cameron Diaz
Drew and Cameron's friendship was cemented on the set of the first Charlie's Angels film in 2000. They both attended each other's weddings and spend time together in LA with their husbands .
Matt Damon and Ben Affleck
Matt and Ben have been best Boston buds since childhood. They even shared a screenwriting Oscar for Good Will Hunting in 1998. The duo are still close friends, having enjoyed many vacations with both their families in recent years.
John Krasinski and Jimmy Kimmel
John and Jimmy are funny friends and neighbors. They kicked off 2012 together in Hawaii with their significant others and joked about the vacation on Jimmy's talk show. John and Jimmy have been pulling pranks on each other for years, and the antics are usually highlighted on Jimmy's show as well.
Lena Dunham and Jemima Kirke
Lena and Jemima have been pals ever since their school days at Brooklyn's St. Ann's School. The two have remained very close over the years, with Lena putting Jemima in her film, Tiny Furniture, and on her hit TV show, Girls.
Robert Pattinson and Tom Sturridge
These two go all the way back to their school days in London. Both guys relocated to the US for their careers around the same time, and they hang out with the same group of British actors in Hollywood.
Jake Gyllenhaal and Marcus Mumford
Jake and the Mumford and Sons singer have been pals for years, with Jake even attending Marcus's 2012 wedding  to Carey Mulligan .
Kim Kardashian and La La Vasquez
Kim and La La's friendship goes back many years, and the duo still likes to sit front row at fashion shows, watch basketball games, and hit the red carpet together.
Kristen Stewart and Scout Taylor-Compton
Kristen counts her Runaways costar Scout as one of her close friends. The two met while auditioning for the same roles when they were starting out in Hollywood, but they haven't let the competition keep them from becoming pals.
Tina Fey and Amy Poehler
The funny ladies shared the screen on Saturday Night Live for years, but their friendship actually got started in the '90s while they were both studying improv in Chicago.
Eva Longoria and Mario Lopez
Despite past rumors that they were a couple, Eva and Mario are actually more like family. Eva considers Mario a brother, while Mario shows support for his "girl" Eva on Twitter.
David Beckham and Gordon Ramsay
David and Gordon's friendship goes beyond just guy time; their families are close and even spent Easter together in 2012.
Beyoncé Knowles and Gwyneth Paltrow
Beyoncé and Gwyneth have been close friends for years. Beyoncé told Harper's Bazaar UK of Gwyneth, "She is what I strive to be one day." In the same publication, Gwyneth returned the compliment by calling Beyoncé "the most talented human being on the planet."
Taylor Swift and Lena Dunham
Taylor and Lena are close pals. The two forged a friendship after Lena tweeted about liking Taylor's music. Taylor even reportedly hosted Lena at her Rhode Island home for a 2014 Memorial Day party.
Leonardo DiCaprio and Tobey Maguire
Leo and Tobey have been catching Lakers games together for years, and Tobey talked about working with Leonardo on 2013's The Great Gatsby. "The fact that I was forced to see one of my best friends every day was fantastic."
Nicole Kidman and Naomi Watts
Nicole and Naomi aren't just fellow Aussie actresses; they're best friends. The ladies were classmates in high school, and their friendship is evident on red carpets to this day. Nicole has said of her friendship with Naomi  that they are "very, very good friends and have maintained that through so many things."
Will Ferrell and John C. Reilly
Will and John have never been shy about their hilarious relationship. The two have starred in several movies together, including Talladega Nights and Step Brothers, and at a Lakers game in 2011, they showed some PDA on the kiss cam.
Woody Harrelson and Matthew McConaughey
Woody and Matthew are longtime friends, and they recently took their relationship to the small screen. Woody and MM were TV costars for the first time in HBO's True Detective, after working together on the big screen in both Edtv and Surfer, Dude.
Justin Bieber and Usher
Justin used to idolize Usher , and now the singer is one of his closest friends. Usher signed Justin to his record label in 2008 and quickly became the teen's mentor. Usher even stood by Justin during some of his more scandalous times.
Salma Hayek and Penélope Cruz
Salma and Penélope have been pals for years and starred together in 2006's Bandidas.
Reese Witherspoon and Kate Winslet
Reese met Kate in 2007, and they've been buddies since. Reese said of their friendship, "Imagine my good fortune when Kate Winslet  moved into my neighborhood, rang my doorbell, and said, 'Dahling, Sam [Mendes] is off shooting and I believe our children are the same age. Could they possibly have a playdate, and, oh, by the way, it's almost 9 o'clock and I've had nothing to drink — do you have any wine?'"
Rihanna and Katy Perry
Rihanna  and Katy are such good friends that Rihanna  was a part of Katy's small bachelorette party back in 2010. They managed to catch up at Coachella in 2012, and they love to get together whenever their busy schedules allow.
Zac Efron and Ashley Tisdale
Zac and Ashley have been buds since their High School Musical days and still spend time together. Ashley even showed her support for Zac at his Lucky One premiere in April 2012.
Lauren Conrad and Lo Bosworth
These two have been besties since their time together on Laguna Beach, and their friendship has lasted through their journey to Hollywood. Lo was even in Lauren's wedding  party!
Katy Perry and Allison Williams
Pals Katy and Allison attended the Grammys together in 2013. Allison said of the date night with Katy , "She's a friend of mine and she's nominated, as she should be. I can't wait to go."
Jennifer Aniston and Chelsea Handler
Jennifer and Chelsea have grown close over the last few years and even have taken vacations to Cabo together.
Jennifer presented Chelsea with a Glamour Woman of the Year honor in 2012. At the show, Jen said, "I rarely comment on my personal life. But I'm here to tell you, I'm madly in love. I'm madly in love with the one and only Chelsea Handler."
Leonardo DiCaprio and Lukas Haas
Leo and Lukas have been buddies since they first met while auditioning in Hollywood years ago. They stick together for sports games and lavish vacations, and they even attended Coachella together in 2011.
Selena Gomez and Lily Collins
Selena and Lily may have both dated Taylor Lautner , but it hasn't stopped the two of them from becoming friends.
Sienna Miller and Channing Tatum
Sienna Miller  and Channing Tatum  became pals after they met on the set of G.I. Joe: The Rise of Cobra. Sienna even said that she has been giving Channing advice on raising a baby now that he and wife Jenna Dewan Tatum are parents.