Joseph Maréchal, SJ (French: [maʁeʃal]; 1 July 1878 – 11 December 1944) was a Belgian Jesuit priest, philosopher, theologian and psychologist.

Maréchal joined the Jesuits in 1895 and after a doctorate in biology at Leuven (1905) he first specialized in experimental psychology, spending some time in Munich with Wilhelm Wundt (1911).

Prompted by the call of Pope Leo XIII to revitalize Thomist theology, he started studying in depth the works of St. Thomas Aquinas in order to understand the inner coherence of his system, along with the works of other scholastic thinkers, modern philosophers and scientists of the day.

From this, and in particular from Kant's transcendental idealism, emerged a new and more dynamic Thomism, recapturing the union of 'act and power' in Aquinas.

The work of Maréchal had a great influence on such contemporary theologians and philosophers as Andre Marc, Gaston Isaye, Joseph de Finance, Karl Rahner, Bernard Lonergan, Johannes Baptist Lotz, Bernard O'Brien and Richard De Smet.