Katherine Marlea Clark (born July 17, 1963) is an American lawyer and politician who has served as the U.S. representative for Massachusetts's 5th congressional district since 2013. She has been House Minority Whip since 2023 and was Assistant House Democratic Leader (known as the "Assistant Speaker") from 2021 to 2023. Her district includes many of Boston's northern and western satellite cities and suburbs, such as Medford, Framingham, Woburn, Waltham, and her home city of Revere. Clark was a member of the Massachusetts House of Representatives from 2008 to 2011 and the Massachusetts Senate from 2011 to 2013.