Réginald Marie Garrigou-Lagrange (; 21 February 1877 – 15 February 1964) was a French Catholic theologian and Dominican friar. He has been noted as a leading neo-Thomist of the 20th century, along with Jacobus Ramírez, Édouard Hugon, and Martin Grabmann. He taught at the Dominican Pontifical University of St. Thomas Aquinas, the "Angelicum", in Rome from 1909 to 1960. There he wrote his magnum opus, "The Three Ages of the Interior Life" (Les Trois Ages de la Vie Interieure) in 1938.