Cornelius Jansen, the Elder (Dutch: [ˈjɑnsən]; 1510, Hulst – 11 April 1576, Ghent) was a Catholic exegete and the first bishop of Ghent.
He received his early education at Ghent from the Brethren of the Common Life (called at Ghent the Hieronymites), and later studied theology and Oriental languages at Leuven. After he had become a licentiate of theology in 1534, he lectured, at the request of the abbot of the Premonstratensian Abbey of Tongerloo, to the young monks on the Holy Scripture until 1542, from which date until 1562 he discharged the duties of pastor of the parish of St. Martin at Courtrai (Kortrijk) with great success. Having finally attained the degree of Doctor of Theology in 1562, he was immediately appointed professor of theology at the Old University of Leuven, became in the following year dean of the collegiate seminary of St. James, and attended the last sessions of the Council of Trent as delegate of the university.
On his return, Philip II of Spain appointed him first bishop of the newly founded See of Ghent, which dated only from 1559. For a long time he refused to assume the dignity, on account of the difficult conditions in the diocese, and was not preconized until 1568, by Pope Pius V. As bishop he devoted himself especially to checking the advance of Protestantism, and to carrying out the decrees of the Council of Trent. With this object in view, he founded a seminary for priests at Ghent in 1569, held diocesan synods in 1571 and 1574, and published a ritual for his diocese.
He was entrusted with the compilation of a ritual to be used in the ecclesiastical province of Mechlin, but did not finish it. While at Tongerloo he wrote a great deal, and, as pastor at Kortrijk, had already become widely known for his exegetical work.