Dum Diversas is a papal bull issued on 18 June 1452 by Pope Nicholas V. Addressed to Afonso V of Portugal, it recognized Portugal's rights to territories it had discovered along the West African coast, and the reduction of the infidels and non-Christians territories to perpetual vassals of the Christian monarch.

Pope Nicholas V, born Tommaso Parentucelli, was head of the Catholic Church and ruler of the Papal States from 6 March 1447 until his death, in March 1455. Pope Eugene IV made him a cardinal in 1446 after successful trips to Italy and Germany, and when Eugene died the next year, Parentucelli was elected in his place. He took his name Nicholas in memory of his obligations to Niccolò Albergati.