Matteo Rosso Orsini (c. 1230 in Rome – 4 September 1305 in Perugia), was a Roman aristocrat, politician, diplomat, and Roman Catholic Cardinal. He was the nephew of Pope Nicholas III (Giovanni Gaetano Orsini) (1277-1280).
Matteo Rosso was the son of Gentile Orsini, Lord of Mugnano, Penna, Nettuno and Pitigliano, who was the son of Matteo Rosso Orsini, "Il Grande" (1178-1246). Matteo's mother was named Costanza. He had two older male siblings, Romano (a Dominican) and Bertoldo, and two older female siblings, Perna (who married Pietro Stefaneschi, Lord of Porto, the parents of Cardinal Giacomo Giovanni Gaetani Stefaneschi) and Angela (who married Guastarano de’ Paparoni, Count of Anguillara). He had a younger brother, Orso, and a sister, Elisabetta (who married Roffredo Caetani, Lord of Sermoneta). His uncle was Cardinal Giovanni Gaetano Orsini, who had been made a cardinal in 1244 and who became Pope Nicholas III in 1277.
The family was very close to S. Francis of Assisi. The Grandfather, Matteo Rosso "Il Grande", had been a member of the Third Order of S. Francis, and Giovanni Gaetano Orsini had been an oblate as a child, and had been named Protector of the Franciscans by Pope Alexander IV.
There is little evidence about Matteo Rosso Orsini's education.
On 4 January 1253, Pope Innocent IV (Fieschi) wrote concerning the testamentary bequests of Cardinal Giovanni Colonna (died 1245), which were being administered by his executor, Cardinal Aegidius de Torres; some 200 marks of Cardinal Colonna's money had been deposited at S. Geneviève in Paris for the benefit of Oddo Colonna, his nephew. The Pope ordered that the 200 marks be paid to Oddo Colonna or his procurator, and that his Subdeacon and Chaplain, Matteo Rosso, Parisius commoranti, be instructed to compel the agents to turn over the money to Oddo Colonna. From this, it is inferred that Matteo Rosso Orsini was studying at the University of Paris.
His name appears in a document of 13 November 1255, in which he is present in a court proceeding before Cardinal Giovanni Gaetano Orsini, his uncle, as Magister Matheus Rubeus, Canon of Laon, Papal chaplain, and providus iuris This indicates that Matteo Rosso had a teaching degree, and that it was in law. It is inferred that he took his degree at Bologna, though there is no evidence for that inference, and there are several of other possibilities. It would appear, however, that his study of the law was rather brief if he was still in Paris at the beginning of 1253, and already working at the Roman Curia in November 1255.
It is said that Matteo Rosso Orsini wrote theological tracts, but it is likely that this statement is the result of a confusion with his nephew and namesake, who was a Dominican and a theologian, and a Cardinal at Avignon (1327-1340).