Glamorous celebrity besties over 40: Courteney Cox and Jennifer Aniston, Cameron Diaz and Drew Barrymore & more

For many of us, our girlfriends are some of the most important people in our lives. They keep us grounded, support us through tough times, and experience life's highs alongside us.

The same is true of some of Hollywood's best-loved stars who have formed inseparable bonds over their years in the spotlight.

From Jennifer Aniston and Courteney Cox 's forever friendship on the set of Friends to Oprah Winfrey and Gayle King 's decades-long bond, join HELLO! in celebrating female friendship as we meet some of the tightest A-list duos around…

Jennifer Aniston, 55, and Courteney Cox, 60

Jennifer and Courteney became besties on the set of Friends in 1994 and have been like family ever since. Jennifer told Us Weekly that her co-star has been there for her through thick and thin. Of course, if we're talking bestie trios, enter Lisa Kudrow to complete Jen and Court's squad.

Cameron Diaz, 51, and Drew Barrymore, 49

Two of Hollywood's best-loved stars have got a watertight connection built on decades of friendship that bud in L.A. Speaking to Katie Couric , Never Been Kissed star Drew said of Cameron : "She has the most amazing heart. She is one of my closest girlfriends, but the way she loves the people around her is really special. She is so giving of herself and so accepting of others."

Oprah Winfrey, 70, and Gayle King, 69

TV stars Oprah Winrey and Gayle King met in 1976 during their time as young journalists on the WJZ station in Baltimore. Reflecting on their close friendship, Oprah once said: "I understand why people think we're gay. There isn't a definition in our culture for this kind of bond between women."

Tina Fey, 54, and Amy Poehler, 52

Two powerhouse women of comedy unite - Tina Fey and Amy Poehler . Amy, who starred alongside Tina Fey in Baby Mama , told Yes Please: "People think of us as a 'comedy team' and I am not quick to correct them. Why wouldn't I want to connect myself to the fiercest and most talented voice in the comedy world?"

Nicole Kidman, 57, and Naomi Watts, 55

Nicole Kidman and Naomi Watts sat down for an appearance on Off Script With The Hollywood Reporter in June but their friendship goes way back. The Moulin Rouge star told the Telegraph : "Naomi Watts and I are very, very good friends and have maintained that through so many things. I think that's really rare, particularly for actresses, and I take a lot of pride in that."

Salma Hayek Pinault, 57, and Penélope Cruz, 50

Besties Salma Hayek Pinault and Penélope Cruz have truly done life together. "She's one of my best friends. We call each other huevos [eggs]. It was because when we were working together, we didn't have children yet, so we used to sleep much more than now. So it was a way to call each other lazy." Penélope told Allure.

Kate Hudson, 45, and Liv Tyler, 47

Goldie Hawn 's daughter Kate met Steven Tyler's daughter at Crossroads School for Arts and Sciences in Santa Monica and the rest is history. The How To Lose A Guy In 10 Days star even calls Liv's dad 'Papa Tyler'.

Jada Pinkett Smith, 52, and Queen Latifah, 54

Jada first saw Queen Latifah as an audience member at one of her rap concerts. They were introduced by the club promoter and have been firm friends since. "Jada and I can have whole conversations where we haven’t really said anything, but we've said a lot," the Taxi star told People.

Sofía Vergara, 52, and Reese Witherspoon, 48

Actresses Sofía Vergara and Reese Witherspoon met on the set of Hot Pursuit where they created a lasting bond. "I liked her from the moment I saw her," the Modern Family star revealed to E! News . Together they have enjoyed exploring Colombian coffee and trying out dance classes.

Mary J. Blige, 53, and Taraji P. Henson, 53

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Mary J. Blige and Taraji P. Henson are so close they share career advice. The 'Family Affair' singer paid tribute to her bestie when she received a star on the Hollywood Walk of Fame saying, "In my mind, that’s rare, because people don’t share and you’re a sharer. So thank you for being a giver and a sharer."