Kristen Angela Johnston (born September 20, 1967) is an American actress. She is known for her role as Sally Solomon in the television series 3rd Rock from the Sun, for which she twice won the Primetime Emmy Award for Outstanding Supporting Actress in a Comedy Series. She also starred as Wilma Flintstone in The Flintstones in Viva Rock Vegas and as Holly Franklin in the sitcom The Exes. She has a recurring role in the television sitcom Mom.