Bonacossa Borri, also known as Bonaca, Bonacorsa, Buonacosa,[1] Bonaccossi, and Bonacosta (1254–1321 CE), was Lady of Milan by marriage from 1269 to 1321.
[2][3] Bonacossa was the daughter of Squarcina Borri[4][5] (1230–1277, also called Scarsini), captain of exiles from Milan from the advent of the Torriani family, and a loyal supporter of the Visconti, and Antonia (1236–?
), daughter of Guglielmo I de Suavis, who married in 1254.
Borri's family was originally from the town of Santo Stefano Ticino together with some feudal lands of nearby Corby.
[8][9] Bonacossa and her husband co-founded of the chapel of St. Thomas in the Basilica of Sant'Eustorgio of Milan, where they were buried, along with their son Stefano and his two daughters Beatrice and Catherine, and the brother of Matteo, Uberto III Visconti.