It's a very small world and the world of celebrities is no different, especially when you find out just how many went to high school with one another. We suppose this is the kind of things that happens in performance art schools and in LA though.

After all, we never rubbed elbows with a soon to be famous person in our public school systems.

Within this list you will find the stars who spent their formative years together, whether they were the best of buds, mortal enemies or were completely unaware of one another's existence.

  • 1

    Robert Downey Jr., Emilio Estevez, Charlie Sheen, Rob Lowe and Sean Penn

    Santa Monica High School

    Robert Downey Jr., Emilio Estevez, Charlie Sheen, Rob Lowe and Sean Penn went to school together in Southern California and were so inseperable that they were referred to as the Brat Pack. In his autobiography, Lowe recalled their friendship, particularly that with the Estevez/Sheen family, writing, "Everybody in their childhood has that family where you know you're going to be there on Christmas Eve and on any given weekend, you're going to be maybe spending the night in the guest bedroom. That was the Sheens' house for me growing up."

    Robert Downey Jr. Emilio Estevez Charlie Sheen Rob Lowe Sean Penn.jpg
  • 2

    Kate Hudson and Cash Warren

    Crossroads High School

    Yup, Kate Hudson went to school with Jessica Alba's producer husband Cash Warren in Santa Monica, California at the same time. Hudson even went back and attended her high school reunion with basketball player Baron Davis who is another famous face from Crossroads.

    Kate Hudson Cash Warren
  • 3

    Robert Pattinson and Tom Sturridge

    The Harrodian School

    Serious-faced Brits Robert Pattinson and Tom Sturridge both went to school together in London and ended up becoming quite good friends while attending the Harrodian School. Although to be fair, in England high school is called college, whereas what we refer to as college is known there as university. Or uni if you're a fan of British dramas.

    Hector Vallenilla, Pacific Coast News
  • 4

    Neil Patrick Harris and Freddie Prinze Jr.

    La Cueva High School

    In our favorite fellow high school pairing, teen heartthrob Freddie Prinze Jr. and adult heartthrob Neil Patrick Harris both attended school in Mexico, with NPH and FPJ graduating three-years apart from one another. The 'How I Met Your Mother' actor graduated in 1991 with Prinze following in 1994.

    Neil Patrick Harris Freddie Prinze Jr
  • 5

    Chaz Bono and Jennifer Aniston

    New York City's High School of Performing Arts

    Way back when Sonny and Cher's son was their daughter, Chastity Bono, he used to hang out with his buddy Jennifer Aniston in New York City. Recalled Aniston of their time together, "Every day a group of us would go to Chaz's house after school," before adding the sad panda making, "I haven't spoken to him in a while."

    Chaz Bono Jennifer Aniston
  • 6

    John Krasinski and BJ Novak

    Newton South High School

    'The Office' co-stars John Krasinski and BJ Novak actually knew one another and even acted together back in high school in Massachusetts. Joked Novak of their HS days, "I think John started acting as a direct result of my casting him in the senior show. So technically, he has me to thank for all of this, right?" Other 'Office' actors who went to school together include Brian Baumgartner (Kevin) and Ed Helms.

    John Krasinski BJ Novak
  • 7

    Nicole Kidman and Naomi Watts

    North Sydney Girls' High School

    Aussie actresses Nicole Kidman and Naomi Watts bonded while at the same all girl school together and are still very close friends to this day. They even appeared in a movie with one another back in 1991 entitled 'Flirting' but are looking to team up again sometime in the future. As Watts explained on the red carpet, "We’ve been looking for a movie to do together for a long time now. But both of us have ... picky tastes. It has to be the right thing."

    Nicole Kidman Naomi Watts
  • 8

    Val Kilmer and Kevin Spacey

    Chatsworth High School

    Actors Kevin Spacey and Val Kilmer went to school and acted together at Chatsworth just outside of LA. Joked Kilmer of Spacey's acting back in their youth, " [He's] proof that you can learn how to act. Because he was horrible when he first started, and now he's so good."

    Val Kilmer Kevin Spacey
  • 9

    Josh Hartnett and Rachael Leigh Cook

    Minneapolis South High School

    In a pairing made in late '90s, early 2000's heaven, Josh Hartnett and Rachel Leigh Cook both attended school with one another in Minneapolis. He was the jerky football player, she the nerdy weird girl, but once he took her hair out of that ponytail and removed her glasses he realized that he loved her all along. Or something. This is probably not actually what went down.

    Josh Hartnett Rachael Leigh Cook
  • 10

    Prince William and Eddie Redmayne

    Eton

    In the fanciest of the fancy, Prince William and actor/singer extraordinaire Eddie Redmayne attended the prestigious boarding school Eton together. Back in April, Redmayne went to a reception at Windsor Castle where he met William's grandmother the Queen but sadly William was off attending to "royal duties" in Scotland and a reunion was not meant to be.

    Prince William Eddie Redmayne