Coadjutor-elect of Baltimore; born at Ruemannsfelden, Bavaria, 18 August, 1753; died at Philadelphia, U.S.A. October, 1793. He was a novice of the Society of Jesus at the time of its suppression and was subsequently ordained priest. In 1787 he left his native land for the American mission at Father Farmer's invitation, and in March, 1787, he was given charge of the German members of St. Mary's congregation in Philadelphia, and of the Catholics scattered through New Jersey. He spent six years in Philaldelphia, and during that time became noted for his learning, zeal, and piety. When it became necessary, owing to the spread of the faith, to appoint a co-adjutor to Bishop Carroll of Baltimore Fr. Grässel was chosen for the office and the petition for his appointment was formally made to Rome, 24 September, 1793. The petition was granted, Grässel thus being the first German-born Catholic appointed to a bishopric in the United States but before the arrival of the brief naming him titular bishop of Samosata (8 Dec., 1793), Grässel had succumbed to yellow fever contracted while attending the victims of the plague which that year ravaged Philadelphia.
Shea, Life and Times of the Most Rev. John Carroll (New York, 1888); Idem, The Catholic Church in the U. S. (New York, 1856); U. S. Cath. Hist. Magazine (New York, Jan, 1887); Woodstock Letters, II, 102; Reuss, Biog. Cyclo. of the Cath. Hierarchy of the U. S. (Milwaukee, 1898).