Blake Lively, Alexis Bledel, America Ferrera & Amber Tamblyn
This girl gang starred together in The Sisterhood of the Traveling Pants, and their sisterhood extended off screen, too. They’ve been in each other’s weddings and celebrated each other’s pregnancies. Amber Tamblyn shared the key to long-time friendships with MTV News: “The four of us are so vastly different that [it] kind of brings us together, in a weird way, because we learn so much from each other, and we're constantly checking in and texting each other for different types of advice. That's what makes really good friendships, when you have key principles that connect you, but then at the same time, you have somebody that can teach you,” she said.