Luis Mariano Montemayor

Luis Mariano Montemayor (born 16 March 1956) is an Argentinian prelate of the Catholic Church who has worked in the diplomatic service of the Holy See since 1991. He began to serve in his present position as Apostolic Nuncio to Ireland in February 2023.

Prior to this, he served as the Apostolic Nuncio to Colombia from September 2018 to February 2023, Apostolic Nuncio to the Democratic Republic of the Congo from 2015 to 2018 and to Senegal, Cape Verde, and Guinea Bissau, as well as Apostolic Delegate to Mauritania from 2008 to 2015.

He was the second Argentinian to be named a nuncio, after Leonardo Sandri. On 17 September of that year he was also appointed Apostolic Nuncio to Guinea-Bissau.

He received his episcopal consecration on 6 August 2008 in Buenos Aires from Archbishop Dominique Mamberti.

On 22 June 2015, Pope Francis named him Apostolic Nuncio to the Democratic Republic of the Congo.

Early in 2018, Archbishop Montemayor, returned to Rome after being declared persona non grata for his criticisms of DRC President Joseph Kabila.

On 27 September 2018, Pope Francis named him Apostolic Nuncio to Colombia.

On 25 February 2023, he was named Apostolic Nuncio to Ireland. He presented his Letters of Credence to President Higgins on 11 May 2023.

He stated in 2024 that the Church in Ireland would undergo a reorganisation, "In due time, and following careful assessment and consultation, the present Dioceses of Tuam and Killala on the one hand, and Elphin and Achonry on the other, may be governed by one Bishop in each case, just as the Dioceses of Galway and Clonfert are today governed by one Bishop. If this process evolves still further, the associated Dioceses may then merge fully under their Bishop, and, in this way, the six Dioceses in the Province of Tuam will eventually become three".

On 11 July 2026, Pope Leo XIV accepted his resignation.