Pietro Grasso (Italian pronunciation: ['pj??tro 'grasso]; born 1 January 1945), also known as Piero Grasso, is an Italian anti-mafia magistrate and politician who served as President of the Senate from 2013 to 2018.Grasso became the Acting President of Italy on 14 January 2015, upon the resignation of Giorgio Napolitano.
He was President until the swearing in of Sergio Mattarella on 3 February.
On 3 December 2017, Grasso was elected Leader of Free and Equal (Liberi e Uguali, LeU), a new left-wing coalition composed by Democratic and Progressive Movement, Italian Left and Possible.