Erba-Odescalchi, or Odescalchi is the name of an Italian aristocratic family, who achieved a prominent position, and moved to Rome, in the 17th century as bankers and finally with the election of Benedetto Odescalchi as Pope Innocent XI in 1676. He reigned until 1689.
The Odescalchi family, of the minor nobility of Como, were determined entrepreneurs, who in 1619 founded a bank with Benedetto's brother and his three uncles in Genoa, the banking capital of Catholic Europe, which quickly grew into a successful money-lending business. After completing his studies in grammar and letters, the 15-year old Benedetto moved to Genoa to take part in the family business as an apprentice. Lucrative economic transactions were established with clients in the major Italian and European cities, such as Nuremberg, Milan, Kraków, and Rome.
Innocent XI was the last male heir, and the family fortune passed to the descendants of his sister Lucrezia Odescalchi, who had married Alessandro Erba in 1621. The title of Prince of the Holy Roman Empire was conferred on their grandson Baldassare Erba-Odescalchi in 1714, and that of Duke of Syrmia in the Kingdom of Hungary as well, with the qualification of Serene Highness. Other religious members of the family were Cardinals Benedetto Erba Odescalchi and Carlo Odescalchi.
The head of the family now bears the titles of Prince Odescalchi, Duke of Syrmium, Prince of Bassano, and others, and he is an Hereditary Magnate of Hungary and a Grandee of Spain. The family owns the Palazzo Odescalchi in Rome, the famous Orsini-Odescalchi Castle in Bracciano, as well as large estates in Italy and Hungary. The castle in Bracciano, although now belonging to the Odescalchi family, was originally an Orsini fortress until it was sold due to family debts.
The Princely family is currently represented by H.S.H. Prince Carlo Odescalchi, Prince of the Holy Roman Empire, Duke of Syrmium, etc. (b. 1954), whose heir is his son Prince Baldassare Odescalchi. The Erba family is allegedly descended from Enrico Erba, Imperial vicar in Milan in 1165, and the Odescalchi trace their line to Giorgio Odescalchi of Como, fl. around 1290.
In the 20th century, Prince Karoly Odescalchi and his son Prince Paul were members of the Hungarian resistance to both Nazism and Communism. 
- Theroff's Online Gotha - entry for the Odescalchi family, with references to current, legitimate members of the princely family
- A. von Reumont, Geschichte der Stadt Rom (Berlin, 1868)
- "Obituary: Prince Paul Odescalchi". Daily Telegraph.
- Original 1922 Almanach de Gotha (edited by Justice Perthes) entry for the Odescalchi family, link to the original universally-recognised genealogical reference document, with details of family honours