03/07/2011 at 01:00 AM EST
JESSICA SEINFELD & MADONNA
The pop star, 52, and the cookbook author, 39, are Hamptons fixtures together-and it helps that their kids like each other too: Madonna
's brood and the Seinfeld kids teamed up to trick-or-treat last Halloween.
JENNIFER GREY & TRACY POLLAN
The actresses, both 50, have been best friends since age 14-and it was Pollan's husband, Michael J. Fox, who egged Grey on to tackle Dancing with the Stars
& Beyoncé Knowles
When Beyonce, 29, married Jay-Z in 2008, Paltrow and husband Chris Martin were among the select few guests. Recently the pair were spotted holding hands at the Grammys (with matching hairdos!). "Beyonce is the most talented human being on the planet," Paltrow, 38, said to Harper's Bazaar U.K.KATY PERRY
What happens in Vegas stays...between BFFs. Last fall Rihanna
, 23, threw Perry, 26, a raucous bachelorette party-strippers included.
CHELSEA HANDLER & JENNIFER ANISTON
The comedian, 36, shares laughs, vacations and margaritas with Aniston, 42. "I adore her," the actress told PEOPLE of her pal of two years. "She's hot, hilarious and has a heart of gold."
KIM HAS TWO!
LALA VAZQUEZ, CIARA & KIM KARDASHIAN
When they're not raiding each other's closets, the trio-singer Ciara, 25, former MTV veejay Vazquez, 31, and E! star Kardashian, 30-"always make time for each other," says Kardashian. "They're the best friends a girl could have."
EMMA STONE & TAYLOR SWIFT
The singer, 21, shows no mercy when it comes to her ex-boyfriends, but she's fiercely loyal to her best gal pal, Easy A
star Stone, 22. "She's the most naturally hilarious person I've ever met," says Swift. "I'm really grateful for my friendship with her."