Peter Roh (born at Conthey (Gunthis) in the canton of Valais, Switzerland, 14 August 1811; d. at Bonn, Germany, 17 May 1872) was a Swiss Jesuit preacher.
Up to his thirteenth year he spoke only French, so that he had to learn German from a German priest in the vicinity before he was able to begin his gymnasial studies in the boarding-school kept by the Jesuits at Brig in Switzerland. Later he became a day-pupil at the gymnasium kept by the Jesuits at Sitten. While here he resolved to enter the Society of Jesus (1829); strange to say the external means of bringing him to this decision was the reading of Pascal's pamphlet Monita Secreta.
He taught the lower gymnasial classes at the lyceum at Fribourg. He was first (1842-45) professor of dogmatics at Fribourg, then at the academy at Lucerne which had just been given to the Jesuits. At the same time he preached and aided as opportunity occurred in missions. These labors were interrupted by the breaking out of the Swiss Sonderbund war, during which he was military chaplain; but after its end he was obliged to flee into Piedmont, from there to Linz and to Gries. Finally he found a safe refuge at Ribeauvillé in Alsace as tutor in the family of his countryman and friend Siegwart-Müller, also expatriated. Here he stayed until 1849.
A professorship of dogmatics at the Catholic University of Leuven only lasted a year. When the Catholic missions for the common people were opened in Germany in 1850 his real labors began; as he said himself, "Praise God, I now come into my element."
He was an extemporaneous speaker; the writing of sermons and addresses was, as he himself confessed, "simply impossible" to him.