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

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."