Oldrado da Tresseno (died 1233) was an Italian politician, podestà (mayor) of Milan in the 13th century. He is responsible for restructuring Piazza dei Mercanti (former city center of Milan in the Middle Ages, located next to what is now Piazza del Duomo) and ordering the construction of Palazzo della Ragione, a prominent historic building of Milan, which served as a broletto (government seat) in the Middle Ages. He is also remembered as a fierce prosecutor of the Cathar heretics.