Isidore-Joseph du Rousseaux (1826–1897) was a bishop of Tournai in Belgium.

He was ordained priest on 8 September 1849, and was appointed to teach in the junior seminary.

He was heavily involved in organising the Catholic Congresses in Mechelen in 1863, 1864, and 1867.

[1] His main concern as bishop was to mollify the partisanship that divided the "liberal" and "ultramontane" clergy of his diocese.

[1] He was instrumental in the 1882 appointment of Désiré-Joseph Mercier to a new Chair of Thomist Philosophy established at the Catholic University of Leuven by papal breve of 25 December 1880.