Bishop of Calahorra (without possession) and Zamora, archbishop of Seville, inquisitor, councilor of state, cardinal. Eleventh son of the third Countess of Lemos, Beatriz de Castro, and her second husband and relative, Álvaro Osorio. He was born on 5th March, 1523 at the city of Valladolid, where his mother used to reside. He studied Humanities, Laws, Morals and Philosophy at the University of Salamanca, for whose rectorship he was elected in 1545, swearing in as a graduate of Canon Law as early as 1552. When he was seventeen years old his father died. On his own initiative and following a common custom in the sixteenth century the cardinal took his mother’s surname, hence he is known as Rodrigo de Castro Osorio.
From 1546, Rodrigo de Castro lived under the protection of his brother, Pedro, who had been promoted to the bishopric of Salamanca and who in 1548 was appointed chaplain to the still Prince Felipe. This second circumstance allowed Rodrigo de Castro to be part of the entourage of the future monarch, who in that year began his great triumphal journey through the territories of the Empire. He did it again in 1554, when he was traveling to England, on the occasion of Felipe’s marriage to Queen Maria Tudor. The following year he went to Rome, commissioned as secretary of papers and ciphered documents to help his other brother, Fernando Ruiz de Castro, Marquis de Sarria, in his difficult but successful embassy to Paulo IV. In 1559, accredited as a skilled diplomat, he returned to Spain and received priestly orders in Cuenca. He first enjoyed various benefits in Galicia, which were the presentation of the House of Lemos, and shortly thereafter he participated directly, as counselor of the Supreme Court of the Inquisition, in the long trial against Archbishop Carranza, archbishop of Toledo and, in late 1564 , he was commissioned by Felipe II to handle in Rome the authorization that would allow the dictation of the sentence to the Inquisition.
After several months of fruitless negotiations, Rodrigo de Castro chose to suggest an intermediate solution: the sending of a special legate with broad powers, which would sentence Carranza in Spain.
When he was fifty years old and after being listed as a canon and cantor of the church in Cuenca, Rodrigo de Castro was appointed to the bishopric of Calahorra, of which he did not take possession, as he was immediately promoted to Zamora, being solemnly consecrated in San Jerónimo el Real, in Madrid, on 7th November, 1574. Four years later, in 1578, he was recommended to the bishopric of Cuenca, which at that time was one of the principal ones in Spain. From here, he played a particularly important role in the debates raised in those years about the succession to the Portuguese throne, an issue especially annoying to him, by the ties of kinship and fondness that united him to the Braganza. However, his good works were decisive in achieving the accord granted in Elvas, on the eve of Christmas of 1580. Soon after, Rodrigo was proposed for governing the archdiocese of Seville; but before taking possession of it, he had to attend to a new royal commission: receiving the Infanta Maria, widow of the Emperor Maximilian II, in Barcelona and then accompanying her to Lisbon, where Philip II had planned to wait for her. After fulfilling the assignment, in which he invested most of the year, Rodrigo remained in Lisbon for nine months, intervening as a witness at the same time in the trial against Antonio Pérez, former royal secretary.
At the end of 1582 he made his public and solemn entrance in Seville, making sure he was accompanied by a large entourage of Galician clerics who would make a career with him there: Dr. Juan García de Vaamonde, García Álvarez de Sotomayor, Álvaro de Losada and Quiroga, Fernando de Maseda , Alonso Buján de Somoza, Pedro de Olea, Francisco de Aguiar, Felipe Osorio de Castro, Alonso de Salves Mariño … and three nephews of his, Diego, Álvaro and Alonso de Ulloa and Osorio, archdeacons respectively of Ecija, Reina and Jerez, who didn’t always behave prudently; in particular, the last one, which was – in the words of Cotarelo – a somewhat corrupt man. Rodrigo seems to have taken note of the case and, from then on, he placed the greatest care in the election and provision of the responsibilities. In December 1583, just over a year after his arrival, Gregorio XIII promoted Rodrigo de Castro to the cardinalate with the title of the Twelve Apostles. He received the Red hat on 7th March, 1585, in the course of a solemn ceremony in the Cathedral of Zaragoza, by Monsignor Ludovico Taberna, papal nuncio in Spain, and before Felipe II himself, the archbishop of Zaragoza and the influential cardinal Granvela.
In the summer of 1598, Rodrigo de Castro moved to the Court, attending the call of Felipe II, who died shortly after his arrival. In Madrid he remained for several months and at the beginning of the year he moved to Valencia, since the late monarch had commissioned him to receive the future Queen Margarita in Vinaroz. Castro returned to Seville in mid-May, after having attended the royal wedding, at whose end he had confirmation that he would not be promoted to the Toledo headquarters, which he had hoped for upon the death of the elected archbishop Garcia de Loaisa.
Cardinal Rodrigo de Castro, whose life would end shortly after his return to Seville, stood out as a generous protector of writers and artists, but his memory survived above all because of his deeds and foundations, all generously provisioned. The Retreat of Lost Girls and the annual Alms for Poor Prisoners are well known in Seville, as well as the shelter granted to the schools of San Hermenegildo and San Gregorio and to other Jesuit foundations in Jerez and Écija. But more than these, those that benefited his native Monforte stood out; Here he finished the Franciscan convent founded by his grandfather, Count Rodrigo Osorio, and continued by his mother, Countess Beatriz, who died without seeing them completed.