Achille Grassi (16 February 1456 – 22 November 1523) was an Italian Roman Catholic bishop and cardinal.

[1] He occupied this see until 1516, when he resigned in favor of Cardinal Giulio de' Medici, the future Pope Clement VII.

[1] In 1507, the pope sent him and Cardinal Antonio Pallavicini Gentili as nuncios to Louis XII of France, who was then in Genoa, to encourage him to make peace with Maximilian I, Holy Roman Emperor.

[1] In 1510, he was nuncio to the Emperor, Vladislaus II of Bohemia and Hungary, and Sigismund I the Old asking for troops to use against the Ottoman Empire and addressing other issues facing the Kingdom of Poland.

[1] On 30 May 1511 he was transferred to the see of Bologna; he occupied this see until 8 January 1518, when he resigned in favor of Cardinal Giulio de' Medici.