Efrem Leone Pio Forni (10 January 1889 – 26 February 1976) was an Italian Cardinal of the Roman Catholic Church.
He received his episcopal consecration on 20 February 1938 from Cardinal Eugenio Pacelli, (elected Pope in 1939) with Archbishops Alberto Levame and Luigi Traglia serving as co-consecrators, in the church of San Carlo al Corso in Rome.
On 8 July 1956, he again served as a papal legate, this time to bestow the Golden Rose on the Grand Duchess of Luxembourg.
In 1962 Pope John XXIII created him Cardinal Priest of Santa Croce in Gerusalemme, and he resigned his diplomatic posts.
From 1962 to 1965, Efrem Cardinal Forni attended the Second Vatican Council, during the course of which he participated in the 1963 papal conclave that selected Pope Paul VI.