Ernesto Nathan (5 October 1848 – 9 April 1921) was an English-Italian politician who was the mayor of Rome from November 1907 to December 1913.

He was attracted by the revolutionary ideas of Giuseppe Mazzini, and in 1870, at 25, he moved to Rome as administrator of La Roma del Popolo.

The first mayor of Rome who did not belong to the land-owning elite which had controlled politics in the city until then, and motivated by a deep belief in the importance of secular, ethical politics, Nathan tried to regulate as much as possible the intense building programs that had erupted all around the city after it became the capital of Italy in 1871.

The 40th anniversary commemoration of the Capture of Porta Pia in 1910 heightened tension between Nathan's anticlerical administration and the Holy See.

With respect to public works, Nathan inaugurated the Vittoriano, the Palace of Justice (Palazzo di Giustizia), the Archaeological Walk on the Aventine and Caelian Hills, and the National Stadium, the current Stadio Flaminio, Rome's first modern building for sports events.