Kelly Clarkson took the stage on Saturday Night Live last night for her third time as musical guest on the show. She performed "Stronger (What Doesn't Kill You)" and "Mr. Know It All," both from her new album Stronger. "I'm a three-peat! I've made it," Clarkson recently told MTV News. "It's a legendary stage! I've been watching it since I was a kid. I think we all have." Clarkson's first appearance on the show was in 2005.