- Born: December 25, 1730 in Poggio a Caiano, Grand Duchy of Tuscany
- Parents: Domenico Mazzei and Elisabetta Mazzei
- Spouse: Maria Martin (m. 1778, d. 1788); Antonia Antoni (m. 1796)
- Children: No biological children recorded; stepdaughter Margherita Maria Martini
- Died: March 19, 1816 in Pisa, Italy
- Highest Office: Virginia State Agent/Diplomat (1779-1784)
- Other Notable Positions: Physician, merchant, horticulturalist, advisor to King Stanisław II of Poland, secret agent for Virginia during Revolutionary War
- Party Affiliation: Not applicable (foreign-born, non-elected positions)
- Historical Note: Italian immigrant whose writings influenced Jefferson’s “All men are created equal” phrase in the Declaration of Independence. Brought Mediterranean agricultural techniques to Virginia and established experimental farms near Monticello.