Smart was nominated for the Tony Award for Best Actress in a Play for the 2000 Broadway revival of "The Man Who Came to Dinner", and would go on to receive two Primetime Emmy Awards for her role as Lana Gardner on the NBC sitcom "Frasier" (2000–01). She won a third Primetime Emmy Award for her starring role as Regina Newley on the ABC sitcom "Samantha Who?" (2007–09). She also portrayed Martha Logan on the action drama series "24" (2006–07). For her performance as Floyd Gerhardt on Noah Hawley's FX crime series "Fargo" (2015), she earned a Critics' Choice Television Award and a Primetime Emmy Award nomination. From 2017 to 2019, she starred as Melanie Bird in the FX science fiction series "Legion", and in 2019, she starred as Laurie Blake (née Juspeczyk) in "Watchmen".