Diego Merino, O. Carm. (1570 – 1 January 1637) was a Catholic prelate who served as Bishop of Isernia (1626–1637)^[1] and Bishop of Montepeloso (1623–1626).^[2][3]

Diego Merino was born in Baeza, Spain in 1570 and ordained a priest in the Order of the Brothers of the Blessed Virgin Mary of Mount Carmel.^[3] On 20 November 1623, he was appointed during the papacy of Pope Paul V as Bishop of Montepeloso.^[2][3] On 26 November 1623, he was consecrated bishop by Giovanni Garzia Mellini, Cardinal-Priest of Santi Quattro Coronati with Alessandro Bosco, Bishop of Gerace, and Tommaso Ximenes, Bishop of Fiesole, serving as co-consecrators.^[3] On 24 August 1626, he was appointed during the papacy of Pope Urban VIII as Bishop of Isernia.^[1][3] He served as Bishop of Isernia until his death on 1 January 1637.^[1][3] While bishop, he was the principal co-consecrator of Giulio Cesare Sacchetti, Bishop of Gravina di Puglia (1623).^[3]