(7 March 1922 – 1 April 2009) was an Italian priest of the Order of Friars Minor who on 24 November 2007 was appointed a cardinal-deacon of the Roman Catholic Church.

He obtained his doctorate in Dogmatic Theology and followed specialised studies at the Catholic University of Louvain in 1951-1951, after which he taught dogmatic theology in the order's study houses in Siena and Fiesole, and again in 1963–1964, after which he was appointed professor at the Pontifical University Antonianum in Rome, where he taught until 1991.

He contributed to the writing of the Dogmatic Constitutions Dei Verbum and Lumen Gentium, and held several posts in the Roman Curia.

On 24 November 2007, Betti was raised to the rank of Cardinal-Deacon and assigned the titular church of Ss.

[1] He died aged 87 at the Provincial Infirmary of St. Francis on the hill of Fiesole, where he had lived since the year 2000.