Agostino Depretis was an Italian statesman and politician. He served as Prime Minister of Italy for several stretches between 1876 and 1887, and was leader of the Historical Left parliamentary group for more than a decade. He is the fourth-longest serving Prime Minister in Italian history, after Benito Mussolini, Giovanni Giolitti and Silvio Berlusconi, and at the time of his death he was the longest-served. Depretis is widely considered one of the most powerful and important politicians in Italian history.

The Left group, later called Historical Left by historians to distinguish it from the left-wing groups of the 20th century, was a liberal and reformist parliamentary group in Italy during the second half of the 19th century. The members of the Left were also known as Democrats or Ministerials. The Left was the dominant political group in the Kingdom of Italy from the 1870s until its dissolution in the early 1910s.