| Bona Sforza | |
|---|---|
 Cameo with bust of Bona Sforza, c. 1540 | |
| Queen consort of Poland Grand Duchess consort of Lithuania | |
| Tenure | 18 April 1518 – 1 April 1548 |
| Coronation | 18 April 1518 Kraków, Poland |
| Duchess regnant of Bari | |
| Tenure | 11 February 1524 – 1557 |
| Predecessor | Isabella |
| Successor | None (annexed by Naples) |
| Born | 2 February 1494 Vigevano, Duchy of Milan |
| Died | 19 November 1557 (aged 63) Bari, Kingdom of Naples |
| Burial | |
| Spouse | |
| Issue Detail | |
| House | Sforza |
| Father | Gian Galeazzo Sforza |
| Mother | Isabella of Aragon |
Bona Sforza (2 February 1494 – 19 November 1557) was Queen of Poland and Grand Duchess of Lithuania as the second wife of Sigismund the Old, and Duchess of Bari and Rossano by her own right. She was a surviving member of the powerful House of Sforza, which had ruled the Duchy of Milan since 1450.
Smart, energetic and ambitious, Bona became heavily involved in the political and cultural life of the Polish–Lithuanian union. To increase state revenue during the Chicken War, she implemented various economic and agricultural reforms, including the far-reaching Wallach Reform in the Grand Duchy of Lithuania. In foreign policy, she allied with the Ottoman Empire and sometimes opposed the Habsburgs. Her descendants became beneficiaries of the Neapolitan sums, a loan to Philip II of Spain that was never completely paid.