Ranuccio II Farnese (17 September 1630 – 11 December 1694) was the sixth Duke of Parma and Piacenza from 1646 until his death nearly 50 years later.

Ranuccio was the eldest son of Odoardo Farnese, the fifth sovereign duke of Parma, and his Tuscan wife, Margherita de' Medici.

As he was a minor and had not yet reached his majority, he ruled the first two years of his reign under the regency of his uncle, Francesco Maria Farnese and his mother.

Innocent accused Ranuccio of the murder and in retaliation, forces loyal to the Pope besieged Castro, and then razed it to the ground.

In the last days of his reign, the Duchy suffered heavily from the presence of Imperial troops, who were fighting in the dispute between Victor Amadeus II of Savoy and France.