Lyda Krewson (born November 14, 1953) is an American retired politician who was the 46th mayor of St. Louis, Missouri. She is a member of the Democratic Party and St. Louis's first female mayor, serving from 2017 to 2021. On November 18, 2020, Krewson announced that she would not seek a second term. From 1997 to 2017, Krewson served as the alderman of St. Louis's 28th ward.