Ada María Magdalena Sierra (born 25 June 1966) is an Argentine architect and politician who served as a National Deputy from 2017 to 2021, elected in Buenos Aires Province. A member of the Justicialist Party, she was elected in 2017 as part of Unidad Ciudadana. Sierra previously served as a member of the Buenos Aires Province Senate from 2015 to 2017, representing the Third Electoral Section. Since 2021, she has been a member of the City Council of Avellaneda, a post she previously held as well.