The House of Osio (Osii) were an Italian noble family who rose to prominence in Lombardy in the 12th century.

[1] Also in 1185 Guglielmo de Oxa was one of the Milan delegates who concluded the treaty with Emperor Frederick at Reggio.

Allied to the Della Torre, the Osii struggled against the Visconti for the hegemony over Milan between the second half of the 13th century and 1311.

A notable member was Bartolomeo, professor of law at the University of Montpellier, who in 1316 counted Petrarch among his pupils.

The entire cost was donated by the Countess as a memorial to her deceased husband, General Egidio Osio.