Matt Damon and Ben Affleck
The two actors became friends when they were children and lived two blocks away from each other in Boston. The duo won a Best Screenplay Oscar in 1988 for their film, "Good Will Hunting," in which they also starred. The best friends also starred in "Dogma" together.

Kristen Wiig and Maya Rudolph
The two friends and "Saturday Night Live" alums starred in "Bridesmaids" and "Friends with Kids" together.

Will Ferrell and John C. Reilly
The two comedians really hit it off on the set of "Talladega Nights" in 2006, and have since starred in "Step Brothers" and "Anchorman 2" together.

Kate Hudson and Liv Tyler
Hudson and Tyler starred in the 2000 film, "Dr. T and the Woman" together, but the two are actually best pals in real life and went to the same high school.

Zac Efron and Dave Franco
Efron and Franco are friends in real life, but also played best friends and frat bros in "Neighbors," and co-starred in "Charlie St. Cloud."

Ansel Elgort and Nat Wolff
Real-life buddies Elgort and Wolff starred in "The Fault in Our Stars" together, and Elgort even made a small appearance in Wolff's latest film, "Paper Towns."

Selena Gomez and Vanessa Hudgens
Hudgens called Gomez one of her best friends in a National Best Friend Day Instagram post this year, and the two starred in "Spring Breakers" together.

Brad Pitt and George Clooney
Pitt and Clooney played partners in crime in "Ocean's Eleven," but are also good pals in real life, riding motorcycles together when Pitt visits Clooney at Lake Como. 

James Franco and Seth Rogen
Their friendship began when they both were cast in the 1999 series, "Freaks and Geeks." Since then, the bromantic friends have teamed up for "This is the End," "The Interview" and "Pineapple Express."

Ben Stiller and Owen Wilson
Not only have Stiller and Wilson been in over 10 movies together, which include "Night at the Museum," "Meet the Parents" and "Zoolander," but they have also been friends for a long time. 

Leonardo DiCaprio and Tobey Maguire
The two actors have been friends for over 25 years, which started when the pair auditioned for a lot of the same roles. Recently, they starred in "The Great Gatsby" together, but also worked on "Don's Plum" and "This Boy's Life" together.

Kevin James and Adam Sandler
Adam Sandler is known to make movies with his best friends, and Kevin James is one of them. They two did "I Now Pronounce You Chuck & Larry," "Grown Ups," and "Pixels" together, to name a few. 

Drew Barrymore and Cameron Diaz
The two became friends during their "Charlie's Angels" days, and have been inseparable ever since.