Désiré-Félicien-François-Joseph Mercier was a Belgian cardinal of the Roman Catholic Church and a noted scholar. A Thomist scholar, he had several of his works translated into other European languages. He was known for his book, Les origines de la psychologie contemporaine (1897). His scholarship gained him recognition from the Pope and he was appointed as Archbishop of Mechelen, serving from 1906 until his death, and was elevated to the cardinalate in 1907.
His contributions to Anglican-Roman Catholic relations include the sponsorship of a series of conversations between 1921 and 1926.