3 Stars Who Are Part of Sam Heughan's Circle of Celebrity Friends

The two actors developed a bromance after William tweeted at Sam. "I liked the show [Outlander] and then heard about this tall handsome guy whom everyone was talking about as the next 007 and I got to tweeting about him a little, and he picked up on it finally because I think he had seen some of my work," William told UK's The Daily Record in 2014. "I met him and took him to lunch. He was great, he brought his girlfriend along, we had lunch, laughed, and I run a charity here called Hollywood Charity Horse Show and he sent me some stuff to auction, including a sweatshirt with his sweat on it."

It's unclear how Sam and Colin became friends, but we can't get enough of them together. In addition to their hilarious back-and-forth banter on Twitter, Colin had to dress up as Sam after losing E! Online's Alpha Male Madness tournament back in 2015. We really hope these two never change.

Sam and Caitriona first met during a chemistry test for Outlander and had "instantaneous" chemistry. "When I first met Sam at our chemistry test, which I always think is quite funny, he was the nicest guy and he just put me at ease," Caitriona told The Wrap back in April 2015. "I was a little nervous and he's just that kind of solid, grounded guy. We had one day in London and we took this big, long walk in Hyde Park, and it was great. We just talked about our lives and sort of about the characters and what we thought and that day I was like, 'This is going to be great. I feel like I've got a really solid friend and amazing costar.' So, I knew it was going to be good stuff."